Answer:
0.003034 s
1.035 m
4.5 m
Explanation:
[tex]f[/tex] = frequency of the tone = 329.6 Hz
[tex]T[/tex] = Time period of the sound wave
we know that, Time period and frequency are related as
[tex]T =\frac{1}{f}\\T =\frac{1}{329.6}\\T = 0.003034 s[/tex]
[tex]v[/tex] = speed of the sound in the air = 341 ms⁻¹
wavelength of the sound is given as
[tex]\lambda =\frac{v}{f} \\\lambda =\frac{341}{329.6}\\\lambda = 1.035 m[/tex]
[tex]v[/tex] = speed of the sound in the water = 1480 ms⁻¹
wavelength of the sound in water is given as
[tex]\lambda =\frac{v}{f} \\\lambda =\frac{1480}{329.6}\\\lambda = 4.5 m[/tex]
A rigid rod is rotating at a constant angular speed about an axis that is perpendicular to one end of the rod. A small ball is fixed to the rod at a distance that is 12 cm from the axis. The centripetal force acting on this ball is 1.7 N. What would be the centripetal force that acts on the ball if the ball were fixed to the rod at a distance of 33 cm from the axis?
Answer:
Fc₂ = 4.675 N
Explanation:
r₁ = 12 cm = 0.12 m
Fc= 1.7 N
Fc = mV²/r = m w² r ( ∴ V= r w )
Fc = m w² r ----------------------- (1)
As angular speed (w) and mass are constant.
let m * w² = k ------------------(2)
Put equation (2) in equation (1).
⇒ Fc = m w² r = k * r ( ∴ m w² = k)
⇒ Fc =k * r ----------------------( 3)
⇒ Fc₁ =k * r₁ = 1.7 N
⇒ k = 1.7/ r = 1.7 / 0.12 N ( as r₁=0.12 m )
⇒ k = 14.17
Centripetal force hen the rod is fixed at 33 cm from the axis:
From equation ( 3 )
Fc₂ = k * r₂
Fc₂ = 14.17 * 0.33 N ( ∴ r₂ = 0.33 m)
Fc₂ = 4.675 N
What force is required to push a block (mass m) up an inclined plane that makes an angle of θ with the horizon at a constant velocity, if the coefficient of friction between the plane and the block is μ? Group of answer choices
a. mg μ cosθ
b. mg (μ cosθ + sinθ)
c. mg (μ sinθ + cosθ)
d. mg (μ cosθ + μ sinθ)
e. mg (μ cosθ + m sinθ)
The force needed to push a block up an incline at a constant velocity is the sum of the gravitational force parallel to the incline and the frictional force, which is mg sin(θ) + μmg cos(θ). So the correct option is e.
Explanation:The force required to push a block of mass m up an inclined plane at an angle θ with the horizon at a constant velocity, given the coefficient of friction between the plane and the block is μ, can be determined by analyzing the forces acting on the block. We need to consider both the component of the block's weight parallel to the incline and the frictional force.
Since the block is moving at a constant velocity, the net force along the incline must be zero. This implies that the applied force must counteract the combined forces of gravity pulling the block down the incline and the frictional force opposing the motion. The gravitational component parallel to the incline is mg sin(θ) and the frictional force is μmg cos(θ). Therefore, the required force F is:
F = mg sin(θ) + μmg cos(θ)
This corresponds to answer choice e.
An object is suspended from a spring with force constant 10 N/m. (c) Find the mass suspended from this spring that would result in a period of 2.4 s on Earth. 0.142 Incorrect: Your answer is incorrect. Use the expression for the period of oscillation for a mass attached to a spring to find the mass of the object. kg (d) Find the mass suspended from this spring that would result in a period of 2.4 s on Mars. 0.142 Incorrect: Your answer is incorrect.
To solve this problem we must use the perioricity equations given as a function of the mass and spring constant. Mathematically this can be expressed as:
[tex]T = 2\pi \sqrt{\frac{m}{k}}[/tex]
m = mass
k = Spring constant
Re-arrange to find the mass we have
[tex]m = \frac{T^2k}{4\pi^2 }[/tex]
Replacing with our values we have that
[tex]m = \frac{2.4^2*10}{4\pi^2}[/tex]
[tex]m = 1.459kg[/tex]
D) Mass is independent of acceleration due to gravity (as you can see at the equation previously given) for this reason the mass suspended on mars is given as the same found. Therefore the mass would be
m = 1.459kg
Final answer:
The mass suspended from the spring that would result in a period of 2.4 s is 0.142 kg.
Explanation:
To find the mass suspended from the spring that would result in a period of 2.4 s, we can use the formula for the period of oscillation:
T = 2π √(m/k)
Where T is the period, m is the mass, and k is the force constant of the spring.
Let's rearrange the formula to solve for m:
m = (T^2 · k) / (4π^2)
Substituting the given values:
m = (2.4^2 · 10) / (4π^2)
m = 0.142 kg
A woman of mass 44 kg jumps off the bow of
a 49 kg canoe that is intially at rest.
If her velocity is 2.5 m/s to the right, what
is the velocity of the canoe after she jumps?
Answer in units of m/sˆı.
Answer:
2.2 m/s to the left
Explanation:
Momentum is conserved, so:
m₁ u₁ + m₂ u₂ = m₁ v₁ + m₂ v₂
0 = (44 kg) (2.5 m/s) + (49 kg) v
v = -2.2 m/s
The canoe will move in the opposite direction of the woman with a velocity of approximately 2.24 m/s.
The velocity of the canoe after the woman jumps off can be determined by using the principle of conservation of momentum, which states that the total momentum before an event must equal the total momentum after the event when no external forces act on the system. In this scenario, the system consists of the woman and the canoe.
Before the woman jumps, the system is at rest, so its initial momentum is zero. When the woman jumps off the canoe to the right with a velocity of 2.5 m/s, by conservation of momentum, the canoe must move in the opposite direction to maintain the total momentum at zero.
The momentum possessed by the woman is given by the product of her mass and velocity (mw×vw).
Similarly, the momentum of the canoe is the product of its mass and its velocity in the opposite direction (mc×vc).
Momenta are equal in magnitude and opposite in direction:
mw ×vw = mc ×vc
Therefore, vc = (mw ×vw) / mc
Substituting the given values:
vc = (44 kg ×2.5 m/s) / 49 kg
= 2.24 m/s
The canoe will move to the left (opposite to the woman's direction) with a velocity of approximately 2.24 m/s.
Calculate how much work is required to launch a spacecraft of mass m from the surface of the earth (mass mE, radius RE) and place it in a circular low earth orbit--that is, an orbit whose altitude above the earth's surface is much less than RE. (As an example, the International Space Station is in low earth orbit at an altitude of about 400 km, much less than RE = 6370 km.) Ignore the kinetic energy that the spacecraft has on the ground due to the earth's rotation.
To solve this problem it is necessary to apply the concepts related to the conservation of energy, through the balance between the work done and its respective transformation from the gravitational potential energy.
Mathematically the conservation of these two energies can be given through
[tex]W = U_f - U_i[/tex]
Where,
W = Work
[tex]U_f =[/tex] Final gravitational Potential energy
[tex]U_i =[/tex] Initial gravitational Potential energy
When the spacecraft of mass m is on the surface of the earth then the energy possessed by it
[tex]U_i = \frac{-GMm}{R}[/tex]
Where
M = mass of earth
m = Mass of spacecraft
R = Radius of earth
Let the spacecraft is now in an orbit whose attitude is [tex]R_{orbit} \approx R[/tex] then the energy possessed by the spacecraft is
[tex]U_f = \frac{-GMm}{2R}[/tex]
Work needed to put it in orbit is the difference between the above two
[tex]W = U_f - U_i[/tex]
[tex]W = -GMm (\frac{1}{2R}-\frac{1}{R})[/tex]
Therefore the work required to launch a spacecraft from the surface of the Eart andplace it ina circularlow earth orbit is
[tex]W = \frac{GMm}{2R}[/tex]
A container of water, diameter 12 cm, has a small opening near the bottom that can be unplugged so that the water can run out. If the top of the tank is open to the atmosphere, what is the exit speed of the water leaving through the hole. The water level is 15 cm above the bottom of the container. The center of the 3.0 diameter hole is 4.0 cm from the bottom. How long does it take the water to hit the ground? How far from the container will the water land?
Answer:
1.32 m
Explanation:
from the given figure we can find the velocity at the hole in the container
let it be v and we know that
then [tex]v= \sqrt{2gh}[/tex]
h= 15-4= 11 cm , g=9.81
[tex]v= \sqrt{2(9.81)(11)}[/tex]
v=14.69 m/s
now using
s=ut+0.5at^2
t= is the time required by water to reach bottom of the container
u = velocity in vertical direction is zero.
therefore,
[tex]0.04= 0\times t+\frac{1}{2}\times9.81\times t^2[/tex]
t= 0.09030 sec
let x be the distance far from the container will the water land
x=vt
x=14.69×0.09030 = 1.32 m
A flat plate is oriented parallel to a 45 m/s airflow at 20°C and atmospheric pressure. The plate is L = 1 m in the flow direction and 0.5 m wide. On one side of the plate, the boundary layer is tripped at the leading edge, and on the other side there is no tripping device. Find the total drag force on the plate.
Answer:
4.192 N
Explanation:
Step 1: Identify the given parameters
Velocity of airflow = 45m/s
air temperature = 20⁰
plate length and width = 1m and 0.5m respectively.
Step 2: calculate drag force due to shear stress, [tex]F_{s}[/tex]
[tex]F_{s} = C_{f} \frac{1}{2} (\rho{U_{o}}WL)[/tex]
Note: The density and kinematic viscosity of air at 20⁰ at 1 atm, is 1.2 kg/m³ and 1.5 X 10⁻⁵ N.s/m²
⇒The Reynolds number ([tex]R_{eL}[/tex]) based on the length of the plate is
[tex]R_{eL} =\frac{VXL}{U}[/tex]
[tex]R_{eL} =\frac{45X1}{1.5 X 10^{-5}}[/tex]
[tex]R_{eL}[/tex] = 3 X10⁶ (flow is turbulent, Re ≥ 500,000)
⇒The average shear stress coefficient ([tex]C_{f}[/tex]) on the "tripped" side of the plate is
[tex]C_{f} = \frac{0.074}{(R_{e})^\frac{1}{5}}[/tex]
[tex]C_{f} = \frac{0.074}{(3 X10^6)^\frac{1}{5}}[/tex]
[tex]C_{f}[/tex] = 0.0038
⇒The average shear stress coefficient ([tex]C_{f}[/tex]) on the "untripped" side of the plate is
[tex]C_{f} = \frac{0.523}{in^2(0.06XR_{e})} -\frac{1520}{R_{e}}[/tex]
[tex]C_{f} = \frac{0.523}{in^2(0.06 X 3X10^6)} -\frac{1520}{3X10^6}[/tex]
[tex]C_{f}[/tex] = 0.0031
The total drag force = [tex]\frac{1}{2}(1.2 X 45^2 X 1 X 0.5 (0.0038 +0.0031)[/tex]
The total drag force is 4.192 N
A glass tea kettle containing 500 g of water is on the stove. The portion of the tea kettle that is in contact with the heating element has an area of 0.090 m2 and is 1.5 mm thick.
At a certain moment, the temperature of the water is 75°C, and it is rising at the rate of 3°C per minute.
What is the temperature of the outside surface of the bottom of the tea kettle?
Neglect the heat capacity of the kettle, and assume that the inner surface of the kettle is at the same temperature as the water inside.
Answer:
77.08 C
Explanation:
[tex]m[/tex] = mass of the water = 500 g = 0.5 kg
[tex]c[/tex] = specific heat of water = 4186 J/(kg °C)
[tex]\Delta T[/tex] = Rate of change of temperature = 3 °C /min = (3/60 ) °C /s = 0.05 °C /s
[tex]k[/tex] = thermal conductivity of glass = 0.84
[tex]A[/tex] = Area of the element = 0.090 m²
[tex]t[/tex] = thickness of the element = 1.5 mm = 0.0015 m
[tex]T_{i}[/tex] = Temperature inside = 75 °C
[tex]T_{o}[/tex] = Temperature outside = ?
Using conservation of energy
Heat gained by water = Heat transferred through glass
[tex]m c \Delta T = \frac{kA(T_{o} - T_{i})}{t} \\(0.5) (4186 (0.05) = \frac{(0.84)(0.090)(T_{o} - 75)}{0.0015} \\104.65 = (50.4)(T_{o} - 75)\\T_{o} = 77.08 C[/tex]
A wire 95.0 mm long is bent in a right angle such that the wire starts at the origin and goes in a straight line to x = 40.0 mm , y = 0, and then in another straight line from x = 40.0 mm , y = 0 to x = 40.0 mm , y = 55.0 mm . The wire is in an external uniform 0.300-T magnetic field in the +z direction, and the current through the wire is 5.10 A , directed from the origin into the wire.
A/Determine the magnitude of the magnetic force exerted by the external field on the wire.
B/Determine the direction of the magnetic force exerted by the external field on the wire measured clockwise from the positive x axis.
C/The wire is removed and replaced by one that runs directly from the origin to the locationx = 20.0mm , y = 35.0mm . If the current through this wire is also 4.90A , what is the magnitude of the magnetic force exerted by the external field on the wire?
D/The wire is removed and replaced by one that runs directly from the origin to the locationx = 20.0mm , y = 35.0mm . If the current through this wire is also 4.90A , what is the magnitude of the direction force exerted by the external field on the wire measured clockwise from the positive x axis.?
Answer:
0.1040512455 N
[tex]36.03^{\circ}\ or\ 323.97^{\circ}in\ CCW\ direction[/tex]
0.05925 N
[tex]29.74^{\circ}\ or\ 330.26^{\circ}in\ CCW\ direction[/tex]
Explanation:
I = Current
B = Magnetic field
Separation between end points is
[tex]l=\sqrt{40^2+55^2}\\\Rightarrow l=68.00735\ mm[/tex]
Effective force is given by
[tex]F=IlB\\\Rightarrow F=5.1\times 68.00735\times 10^{-3}\times 0.3\\\Rightarrow F=0.1040512455\ N[/tex]
The force is 0.1040512455 N
[tex]tan\theta=\dfrac{55}{40}\\\Rightarrow \theta=tan^{-1}\dfrac{55}{40}\\\Rightarrow \theta=53.97^{\circ}[/tex]
The angle the force makes is given by
[tex]\alpha=\theta-90\\\Rightarrow \alpha=53.97-90\\\Rightarrow \alpha=-36.03^{\circ}\ or\ 323.97^{\circ}in\ CCW\ direction[/tex]
The direction is [tex]36.03^{\circ}\ or\ 323.97^{\circ}in\ CCW\ direction[/tex]
[tex]F=IlB\\\Rightarrow F=4.9\times \sqrt{20^2+35^2}\times 10^{-3}\times 0.3\\\Rightarrow F=0.05925\ N[/tex]
The force is 0.05925 N
[tex]tan\theta=\dfrac{35}{20}\\\Rightarrow \theta=tan^{-1}\dfrac{35}{20}\\\Rightarrow \theta=60.26^{\circ}[/tex]
[tex]\alpha=\theta-90\\\Rightarrow \alpha=60.26-90\\\Rightarrow \alpha=-29.74^{\circ}\ or\ 330.26^{\circ}in\ CCW\ direction[/tex]
The direction is [tex]29.74^{\circ}\ or\ 330.26^{\circ}in\ CCW\ direction[/tex]
A. Magnitude of the force: [tex]\( 0.104 \, \text{N} \)[/tex]
B. Direction of the force: [tex]\( 323.8^\circ \)[/tex]
C. Magnitude of the force: [tex]\( 0.0593 \, \text{N} \)[/tex]
D. Direction of the force: [tex]\( 330^\circ \)[/tex]
Part A: Determine the magnitude of the magnetic force exerted by the external field on the wire
Given: Length of wire segments: [tex]\( L_1 = 40.0 \, \text{mm} = 0.040 \, \text{m} \) and \( L_2 = 55.0 \, \text{mm} = 0.055 \, \text{m} \)[/tex]
- Magnetic field, [tex]\( B = 0.300 \, \text{T} \)[/tex]
- Current, [tex]\( I = 5.10 \, \text{A} \)[/tex]
The force on a current-carrying wire in a magnetic field is given by [tex]\( \mathbf{F} = I (\mathbf{L} \times \mathbf{B}) \).[/tex]
For the first segment along the x-axis:
- [tex]\( \mathbf{L}_1 = 0.040 \, \text{m} \, \hat{i} \)[/tex]
[tex]\( \mathbf{B} = 0.300 \, \text{T} \, \hat{k} \)[/tex]
[tex]\[ \mathbf{F}_1 = I (\mathbf{L}_1 \times \mathbf{B}) = 5.10 \, \text{A} \times (0.040 \, \hat{i} \times 0.300 \, \hat{k}) \][/tex]
[tex]\[ \mathbf{F}_1 = 5.10 \times 0.040 \times 0.300 \, \hat{j} \][/tex]
[tex]\[ \mathbf{F}_1 = 0.0612 \, \text{N} \, \hat{j} \][/tex]
For the second segment along the y-axis:
[tex]- \( \mathbf{L}_2 = 0.055 \, \text{m} \, \hat{j} \)[/tex]
[tex]- \( \mathbf{B} = 0.300 \, \text{T} \, \hat{k} \)[/tex]
[tex]\[ \mathbf{F}_2 = I (\mathbf{L}_2 \times \mathbf{B}) = 5.10 \, \text{A} \times (0.055 \, \hat{j} \times 0.300 \, \hat{k}) \][/tex]
[tex]\[ \mathbf{F}_2 = 5.10 \times 0.055 \times (-0.300) \, \hat{i} \][/tex]
[tex]\[ \mathbf{F}_2 = -0.08415 \, \text{N} \, \hat{i} \][/tex]
The net force [tex]\(\mathbf{F} = \mathbf{F}_1 + \mathbf{F}_2\)[/tex]:
[tex]\[ \mathbf{F} = -0.08415 \, \hat{i} + 0.0612 \, \hat{j} \][/tex]
The magnitude of the force is:
[tex]\[ |\mathbf{F}| = \sqrt{(-0.08415)^2 + (0.0612)^2} \][/tex]
[tex]\[ |\mathbf{F}| = \sqrt{0.00708 + 0.00375} \][/tex]
[tex]\[ |\mathbf{F}| = \sqrt{0.01083} \][/tex]
[tex]\[ |\mathbf{F}| \approx 0.104 \, \text{N} \][/tex]
Part B: The direction of the force can be found using the angle [tex]\( \theta \)[/tex] with respect to the positive x-axis:
[tex]\[ \theta = \tan^{-1} \left( \frac{F_y}{F_x} \right) \][/tex]
[tex]\[ \theta = \tan^{-1} \left( \frac{0.0612}{-0.08415} \right) \][/tex]
[tex]\[ \theta = \tan^{-1} \left( -0.727 \right) \][/tex]
[tex]\[ \theta \approx -36.2^\circ \][/tex]
Since this angle is measured counterclockwise from the positive x-axis, the direction clockwise is:
[tex]\[ 360^\circ - 36.2^\circ = 323.8^\circ \][/tex]
Part C: Determine the magnitude of the magnetic force exerted by the external field on the wire
For the wire directly from the origin to [tex]\( x = 20.0 \, \text{mm}, y = 35.0 \, \text{mm} \):[/tex]
- Length [tex]\( L = \sqrt{(20.0 \, \text{mm})^2 + (35.0 \, \text{mm})^2} = \sqrt{(0.020 \, \text{m})^2 + (0.035 \, \text{m})^2} \)[/tex]
- Length [tex]\( L = \sqrt{0.0004 + 0.001225} = \sqrt{0.001625} \)[/tex]- Length [tex]\( L \approx 0.0403 \, \text{m} \)[/tex]
[tex]\[ \mathbf{L} = 0.0403 \, \text{m} \][/tex]
Given current [tex]\( I = 4.90 \, \text{A} \)[/tex]:
[tex]\[ \mathbf{F} = I L B \sin(\theta) \][/tex]
[tex]\[ \theta = \angle \text{between } \mathbf{L} \text{ and } \mathbf{B} = 90^\circ \][/tex]
[tex]\[ \mathbf{F} = 4.90 \times 0.0403 \times 0.300 \][/tex]
[tex]\[ \mathbf{F} \approx 0.0593 \, \text{N} \][/tex]
Part D: - Current: [tex]\( 4.90 \, \text{A} \)[/tex]
- Magnetic field: [tex]\( 0.300 \, \text{T} \, \hat{k} \)[/tex]
- Displacement vector: [tex]\( \mathbf{L} = 0.020 \, \hat{i} + 0.035 \, \hat{j} \)[/tex]
- Force vector: [tex]\( \mathbf{F} = I (\mathbf{L} \times \mathbf{B}) \)[/tex]
[tex]\[ \mathbf{L} \times \mathbf{B} = (0.020 \, \hat{i} + 0.035 \, \hat{j}) \times 0.300 \, \hat{k} \][/tex]
[tex]\[ \mathbf{F} = 4.90 (0.020 \, \hat{i} + 0.035 \, \hat{j}) \times 0.300 \, \hat{k} \][/tex]
[tex]\[ \mathbf{F} = 4.90 \times (0.020 \times 0.300 \, \hat{j} - 0.035 \times 0.300 \, \hat{i}) \][/tex]
[tex]\[ \mathbf{F} = 4.90 \times (0.006 \, \hat{j} - 0.0105 \, \hat{i}) \][/tex]
[tex]\[ \mathbf{F} = 0.0294 \, \hat{j} - 0.05145 \, \hat{i} \][/tex]
The magnitude of the force:
[tex]\[ |\mathbf{F}| = \sqrt{(0.0294)^2 + (-0.05145)^2} \approx 0.0593 \, \text{N} \][/tex]
The angle with respect to the x-axis:
[tex]\[ \theta = \tan^{-1} \left( \frac{0.0294}{-0.05145} \right) = \tan^{-1} \left( -0.571 \right) \approx -30^\circ \][/tex]
The direction clockwise is:
[tex]\[ 360^\circ - 30^\circ = 330^\circ \][/tex]
Thermopane window is constructed, using two layers of glass 4.0 mm thick, separated by an air space of 5.0 mm.
If the temperature difference is 20° C from the inside of the house to the outside air, what is the rate of heat flow through this window?
(Thermal conductivity for glass is 0.84 J/s⋅m⋅°C and for air 0.023 4 J/s⋅m⋅°C.)
a. 7 700 Wb. 1 900 Wc. 547 Wd. 180 W
To solve this problem it is necessary to apply the concepts related to rate of thermal conduction
[tex]\frac{Q}{t} = \frac{kA\Delta T}{d}[/tex]
The letter Q represents the amount of heat transferred in a time t, k is the thermal conductivity constant for the material, A is the cross sectional area of the material transferring heat, [tex]\Delta T[/tex], T is the difference in temperature between one side of the material and the other, and d is the thickness of the material.
The change made between glass and air would be determined by:
[tex](\frac{Q}{t})_{glass} = (\frac{Q}{t})_{air}[/tex]
[tex] k_{glass}(\frac{A}{L})_{glass} \Delta T_{glass} = k_{air}(A/L)_{air} \Delta T_{air}[/tex]
[tex]\Delta T_{air} = (\frac{k_{glass}}{k_{air}})(\frac{L_{air}}{L_{glass}}) \Delta T_{glass}[/tex]
[tex]\Delta T_{air} = (\frac{0.84}{0.0234})(\frac{5}{4}) \Delta T_{glass}[/tex]
[tex]\Delta T_{air} = 44.9 \Delta T_{glass}[/tex]
There are two layers of Glass and one layer of Air so the total temperature would be given as,
[tex]\Delta T = \Delta T_{glass} +\Delta T_{air} +\Delta T_{glass}[/tex]
[tex]\Delta T = 2\Delta T_{glass} +\Delta T_{air}[/tex]
[tex]20\°C = 46.9\Delta T_{glass}[/tex]
[tex]\Delta T_{glass} = 0.426\°C[/tex]
Finally the rate of heat flow through this windows is given as,
[tex]\Delta {Q}{t} = k_{glass}\frac{A}{L_{glass}}\Delta T_{glass}[/tex]
[tex]\Delta {Q}{t} = 0.84*24*10 -3*0.426[/tex]
[tex]\Delta {Q}{t} = 179W[/tex]
Therefore the correct answer is D. 180W.
On a bet, you try to remove water from a glass by blowing across the top of a vertical straw immersed in the water. What is the minimum speed you must give the air at the top of the straw to draw water upward through a height of 1.6cm?
Answer:
v₂ = 0.56 m / s
Explanation:
This exercise can be done using Bernoulli's equation
P₁ + ½ ρ v₁² + ρ g y₁ = P₂ + ½ ρ v₂² + ρ g y₂
Where points 1 and 2 are on the surface of the glass and the top of the straw
The pressure at the two points is the same because they are open to the atmosphere, if we assume that the surface of the vessel is much sea that the area of the straw the velocity of the surface of the vessel is almost zero v₁ = 0
The difference in height between the level of the glass and the straw is constant and equal to 1.6 cm = 1.6 10⁻² m
We substitute in the equation
[tex]P_{atm}[/tex] + ρ g y₁ = [tex]P_{atm}[/tex] + ½ ρ v₂² + ρ g y₂
½ v₂² = g (y₂-y₁)
v₂ = √ 2 g (y₂-y₁)
Let's calculate
v₂ = √ (2 9.8 1.6 10⁻²)
v₂ = 0.56 m / s
A loop-the-loop has a circular arc, with a marble that can run along a track and traverse the entire inside of the loop. When the marble is precisely at the top of the inside loop, it has its minimum speed. ~v What do we know about the direction of the net force on the marble at this point, the top of the loop? a. The net force is instantaneously in the direction of the marble’s velocity b. The net force is instantaneously in the opposite direction to the marble’s velocity ~v. c. The net force is vertically downward. d. The net force is vertically upward
Answer:
c. The net force is vertically downward.
Explanation:
At the top of the loop, the only external force that keeps the ball moving around the loop, is the centripetal force.
Now, this centripetal force, is not a " new" force, it's just the vector sum of the two external forces (neglecting friction) , that act simultaneously on the marble, making it to change its speed, in magnitude and direction: the gravity force (which it is always downward), and the normal force(which is always perpendicular to the contact surface, preventing that the marble comes trough the surface), in this case between the marble and the track, which, at the top of the loop, points down too.
So, the net force, exactly at the top of the loop, is vertically downward.
A particular cylindrical bucket has a height of 36.0 cm, and the radius of its circular cross-section is 15 cm. The bucket is empty, aside from containing air. The bucket is then inverted so that its open end is down and, being careful not to lose any of the air trapped inside, the bucket is lowered below the surface of a fresh-water lake so the water-air interface in the bucket is 20.0 m below the surface of the lake.
To keep the calculations simple, use g = 10 m/s2, atmospheric pressure = 1. 105 Pa, and the density of water as 1000 kg/m3.a. If the temperature is the same at the surface of the lake and at a depth of 20.0 m below the surface, what is the height of the cylinder of air in the bucket when the bucket is at a depth of 20.0 m below the surface of the lake?b. If, instead, the temperature changes from 300 K at the surface of the lake to 275 K at a depth of 20.0 m below the surface of the lake, what is the height of the cylinder of air in the bucket?
Answer:
12 cm
Explanation:
[tex]P_1[/tex] = Initial pressure = [tex]P_a=1\times 10^5\ Pa[/tex]
[tex]P_2[/tex] = Final pressure = [tex]P_a+\rho_w gh[/tex]
h = Depth of cylinder = 36 cm
g = Acceleration due to gravity = 10 m/s²
[tex]\rho_w[/tex] = Density of water = 1000 kg/m³
[tex]h_1[/tex] = Depth of lake = 20 m
From the ideal gas relation we have
[tex]P_1V_1=P_2V_2\\\Rightarrow P_a(\pi r^2h)=(P_a+\rho_w gh_1)\pi r^2h'\\\Rightarrow 1\times 10^5\times 36=(1\times 10^5+1000\times 10\times 20)h'\\\Rightarrow h'=\dfrac{1\times 10^5\times 36}{1\times 10^5+1000\times 10\times 20}\\\Rightarrow h'=12\ cm[/tex]
The height of the cylinder of air in the bucket when the bucket is at the given depth is 12 cm
A particular car engine operates between temperatures of 440°C (inside the cylinders of the engine) and 20°C (the temperature of the surroundings). Given these two temperatures, what is the maximum possible efficiency the car can have? (Note that actual car engine efficiencies are in the 20-25% range.) _______ %.
One of the concepts to be used to solve this problem is that of thermal efficiency, that is, that coefficient or dimensionless ratio calculated as the ratio of the energy produced and the energy supplied to the machine.
From the temperature the value is given as
[tex]\eta = 1-\frac{T_L}{T_H}[/tex]
Where,
T_L = Cold focus temperature
T_H = Hot spot temperature
Our values are given as,
T_L = 20\° C = (20+273) K = 293 K
T_H = 440\° C = (440+273) K = 713 K
Replacing we have,
[tex]\eta = 1-\frac{T_L}{T_H}[/tex]
[tex]\eta = 1-\frac{293}{713}[/tex]
[tex]\eta = 0.589[/tex]
Therefore the maximum possible efficiency the car can have is 58.9%
A piccolo and a flute can be approximated as cylindrical tubes with both ends open. The lowest fundamental frequency produced by one kind of piccolo is 516.1 Hz, and that produced by one kind of flute is 257.0 Hz. What is the ratio of the piccolo's length to the flute's length?
Answer:
0.49806
Explanation:
v = Velocity of wave
L = Length of tube
p denotes piccolo
f denotes flute
The fundamental frequency with both ends open is given by
[tex]f=\dfrac{v}{2L}\\\Rightarrow L=\dfrac{v}{2f}[/tex]
It can be seen that
[tex]L\propto \dfrac{1}{f}[/tex]
So,
[tex]\dfrac{L_p}{L_f}=\dfrac{f_f}{f_p}\\\Rightarrow \dfrac{L_p}{L_f}=\dfrac{257}{516} \\\Rightarrow \dfrac{L_p}{L_f}=0.49806[/tex]
The ratio of the piccolo's length to the flute's length is 0.49806
When you drive a car in a circle at a constant speed you are accelerating towards the center of your circular motion.
Answer:True
Explanation:
The given statement is true because when we drive a car in a circle with constant speed , the car experiences the centripetal acceleration towards the center.
But acceleration is change in velocity of object in a given time, here direction of velocity is constantly changing to give rise to acceleration.
If the magnitude of velocity is changing with time then the car would have experiences the tangential acceleration .
How much heat energy is required to vaporize a 1.0-g ice cube at 0°C? The heat of fusion of ice is 80 cal/g.
The heat of vaporization of water is 540 cal/g, and cwater = 1.00 cal/g⋅°C.
a. 620 cal
b. 720 cal
c. 820 cal
d. 1 kcal
The heat required to convert 1.0-g of ice cube at 0°C to vapor is 720 cal.
We know that when heat is supplied to a substance, change of state occurs as the object moves from a particular state of matter to another. The heat required to convert 1.0-g of ice cube at 0°C to vapor is obtained from;
H = mLfus + mcdT + mLvap
H = (1 g * 80 cal/g) + (1 g * 1.00 cal/g⋅°C * (100 - 0)) + (1 g * 540 cal/g)
H = 80 cal + 100 cal + 540 cal
H = 720 cal
The heat required to convert 1.0-g of ice cube at 0°C to vapor is 720 cal.
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The total amount of heat required to vaporize a 1-g ice cube at 0°C considering the stages of heat of fusion, heating up water, and heat of vaporization is 720 cal.
Explanation:To calculate the total amount of heat energy required to vaporize a 1.0-g ice cube at 0°C, we need to consider the heat added to turn the ice into water (heat of fusion), heat to raise the temperature of that water from 0°C to 100°C, and finally heat to turn the water into steam (heat of vaporization).
First, we use the heat of fusion of ice, which is 80 cal/g, thus the heat needed to turn 1g of ice into water at 0°C is 1g * 80 cal/g = 80 cal.
Secondly, to raise the water temperature from 0 to 100°C, we use cwater = 1.00 cal/g⋅°C, thus the required heat is 1g * 100°C * 1.00 cal/g⋅°C = 100 cal.
Finally, we use the heat of vaporization of water which is 540 cal/g, for 1g of water, the heat needed is 1g * 540 cal/g = 540 cal.
Adding all those up give us a total heat of 80 cal + 100 cal + 540 cal = 720 cal.
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You are using a Geiger counter to measure the activity of a radioactive substance over the course of several minutes. If the reading of 400. counts has diminished to 100. counts after 90.3 minutes, what is the half-life of this substance?
Answer : The half-life of this substance will be, 45 minutes.
Explanation :
First we have to calculate the value of rate constant.
Expression for rate law for first order kinetics is given by:
[tex]k=\frac{2.303}{t}\log\frac{a}{a-x}[/tex]
where,
k = rate constant = ?
t = time passed by the sample = 90.3 min
a = initial amount of the reactant = 400
a - x = amount left after decay process = 100
Now put all the given values in above equation, we get
[tex]k=\frac{2.303}{90.3min}\log\frac{400}{100}[/tex]
[tex]k=1.54\times 10^{-2}\text{ min}^{-1}[/tex]
Now we have to calculate the half-life of substance, we use the formula :
[tex]k=\frac{0.693}{t_{1/2}}[/tex]
[tex]1.54\times 10^{-2}\text{ min}^{-1}=\frac{0.693}{t_{1/2}}[/tex]
[tex]t_{1/2}=45min[/tex]
Therefore, the half-life of this substance will be, 45 minutes.
A student stands on the edge of a merry-go-round which rotates five times a minute and has a radius of two meters one evening as the sun is setting. The student produces a shadow on the nearby building. (a) Write an equation for the position of the shadow. (b) Write an equation for the velocity of the shadow.
To solve this problem it is necessary to apply the concepts related to the simple harmonic movement, to the speed in terms of displacement and the timpo, as well as the angular frequency and the period of frequency.
PART A) According to the description given, 5 revolutions are made in one minute (or 60 seconds) that is to say that the frequency would be given by
[tex]f = \frac{1}{12s^{-1}}[/tex]
Therefore the angular velocity can be found as
[tex]\omega = 2\pi f[/tex]
[tex]\omega = 0.52rad/s[/tex]
The displacement that determines the maximum displacement based on the angular velocity time and the time in the simple harmonic movement, is equal to the radius of the circle, in other words
[tex]x = Acos(\omega t)[/tex]
Where,
A = Amplitude
[tex]\omega =[/tex] Angular velocity
t = time
If for our given values the value of the amplitude is 2m and the value of the angular velocity is 0.52rad/s
[tex]x = 2cos(0.52t)[/tex]
So the equation for the position of the shadow is of
[tex]x(t) = 2cos(0.52t)[/tex]
PART B) The equation for the velocity of the shadow is calculated as a expression of the displacement against the time, if we differenciate the previous value found, we have that,
[tex]\frac{dx}{dt} = \frac{d(2cos(0.52t))}{dt}[/tex]
[tex]v(t) = 2(-0.52)sin(0.523t)[/tex]
[tex]v(t) = -1.05sin(0.52t)[/tex]
The position of the shadow can be described using the equation x=2cos(10πt+φ) and the velocity of the shadow can be described using the equation v=-2*10π*sin(10πt+φ), using principles of simple harmonic motion.
Explanation:The subject of this question involves physics and in particular, kinematics and rotational motion, as it relates to the shadow produced by a student standing on a rotating merry-go-round.
The position and velocity of the shadow will vary as the merry-go-round rotates, and these can be represented using mathematical equations. Let's denote the angular speed of the merry-go-round as 'w', which is given by the formula w = 2πn, where n is the number of rotations per minute. For the given question, n = 5 rotations per minute. Therefore, w = 10π rad/min.
(a) Position of the shadow: We can describe the position of the shadow in terms of simple harmonic motion - as the merry-go-round rotates, the shadow produced on the nearby building would be oscillating back and forth. This kind of motion can be mathematically represented as x=Acos(wt+φ), where x is the position of the shadow, A is the amplitude (which is the radius of the merry-go-round, hence 2 meters), w is the angular frequency, t is time, and φ is the phase constant.
(b) Velocity of the shadow: The velocity of the shadow is the derivative of the position with respect to time, which can be represented as v=-Aw*sin(wt+φ). In our case, the angular speed w = 10π rad/min, A is the amplitude (radius of the merry-go-round, hence 2 meters), and 't' is the time.
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In order to study the long-term effects of weightlessness, astronauts in space must be weighed (or at least "massed"). One way in which this is done is to seat them in a chair of known mass attached to a spring of known force constant and measure the period of the oscillations of this system. The 36.2kg chair alone oscillates with a period of 1.15s , and the period with the astronaut sitting in the chair is 2.20s
Part A: Find the force constant of the spring.
Part B: Find the mass of the astronaut.
Answer:
a. K = 1080.61 N/m
b. mₐ = 96.28 kg
Explanation:
T = 2π * √ m / K
T₁ = 2π * √m₁ / K , T₂ = 2π * √m₂ / K
m₁ = 36.2 kg , m₂ = m₁ + mₐ
T₁ = 1.15 s , T₂ = 2.2 s
Equal period to determine the force constant of the spring
a.
K = 4π²* m₁ / T₁²
K = 4π² * 36.2 kg / 1.15² s
K = 1080.61 N/m
So replacing and solve can find m₂
b.
m₂ = T₂² * m₁ / T₁² ⇒ m₂ = 2.20² s * 36.2 kg / 1.15 ² s
m₂ = 132.48
mₐ = m₂ - m₁
mₐ = ( 132.48 - 36.2 ) kg = 96.28 kg
A 4-kg block is sliding down a plane as pictured, with the plane forming a 3-4-5 right triangle. Initially, the block is not moving. (However, we will assume only kinetic friction applies.) The coefficient of static friction between the block and the plane is 0.25. How long does it take for the block to reach the bottom of the plane? (Pick the answer closest to the true value.)A. 3.2 secondsB. 1.6 secondsC. 2.5 secondsD. 1.0 secondsE. 0.5 seconds
Answer:b
Explanation:
Given
mass of block [tex]m=4 kg[/tex]
coefficient of static friction [tex]\mu =0.25 [/tex]
height of triangle is [tex]h=3 m[/tex]
[tex]F_{net}=mg\sin \theta -\mu _kmg\cos \theta [/tex]
[tex]a_{net}=g\sin \theta -\mu _kg\cos \theta [/tex]
[tex]a_{net}=9.8\sin 37-0.25\times 9.8\times \cos 37[/tex]
[tex]a_{net}=5.897-1.956=3.94 m/s^2[/tex]
here [tex]s=5 m[/tex]
[tex]v^2-u^2=2 a_{net}s[/tex]
[tex]v=\sqrt{2\times 3.94\times 5}[/tex]
[tex]v=6.27 m/s[/tex]
time taken to reach bottom of plane
[tex]v=u+at[/tex]
[tex]6.27=0+3.94\times t[/tex]
[tex]t=1.59 s\approx 1.6 s[/tex]
Isolating a variable in two equations is easiest when one of them has a coefficient of 1. Let's say we have the two equations 3A−B=5 2A+3B=−4 and want to isolate one of the variables, such that it appears by itself on one side of the equation. Which of the following is an equation with one of the above variables isolated?
Answer:
[tex]B=3A-5[/tex]
Explanation:
Variable Isolation
It's a common practice when dealing with equations that we have to isolate one variable in terms of other variables and/or constants. The isolation of the variable usually implies adding, subtracting, multiplying or dividing by constants. The following example shows how to isolate the A:
[tex]2A+3B=-4\\\\2A=-4-3B\\\\\displaystyle A=\frac{-4-3B}{2}[/tex]
We are required to find the equation where the variable has a coefficient of 1 and isolate it. The following equation fits into the description:
[tex]3A-B=5[/tex]
Isolating B:
[tex]B=3A-5[/tex]
Manufacturers of headache remedies routinely claim that their own brands are more potent pain relievers than the competing brands. Their way of making the comparison is to compare the number of molecules in the standard dosage. Tylenol uses 325 mg of acetaminophen (C8H9NO2) as the standard dose, while Advil uses 2.00 x 102 mg of ibuprofen (C13H18O2). Find the number of molecules of pain reliever in the standard doses of
(a) Tylenol and
(b) Advil.
a) 12.95*10^20 molecules
b) 5.84*10^20 molecules
Explanation:
a)Tylenol
Mass of Tylenol = 325 mg
(m)=325*10^-3 g
Molecular weight of Tylenol(M) = 151.16256 g/mol
the number of moles present
n = m/M
= 325*10^-3 g /151.1656 g/mol
= 2.15 *10^-3 mol
the number of molecules present
N= nNa
=(2.15*10^ -3 mol)(6.023*10^23 molecules/mol)
N=12.95*10 ^20 molecules
b)Advil
Mass of Advil = 200 mg
m=200*10^-3 g
Molecular weight of Advil(M) =206.28082 g/mol
the number of moles
n=m/M
=200*10^ -3 g/ 206.28082 g/mol
=0.96955*10^ -3 mol
the number of molecules resent
N=nNa
=(0.96955*10^ -3)(6.023*10^ 23 molecules/ mol)
N=5.84*10^20 molecules
Tylenol contains more molecules of active ingredient hence it is a more effective drug.
We have to find the number of molecules in each of the drugs. In the drug, tylenol, the molar mass of the compound C8H9NO2 is;
8(12) + 9(1) + 14 + 2(16) = 96 + 9 + 14 + 32 =151 g/mol
Number of moles = 325 × 10^-3 g/151 g/mol = 0.0022 moles
1 mole contains 6.02 × 10^23 molecules
0.0022 moles contains 0.0022 moles × 6.02 × 10^23 molecules /1 mole = 1.32 × 10^21 molecules
For Advil;
Molecular mass= 13(12) + 18(1) + 2(16) = 156 + 18 + 32 = 206 g/mol
Number of moles = 0.2 g/ 206 g/mol = 0.00097 moles
1 mole contains 6.02 × 10^23 molecules of advil
0.00097 moles contains 0.00097 moles × 6.02 × 10^23 molecules /1 mole = 5.8 × 10^20
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A geneticist looks through a microscope to determine the phenotype of a fruit fly. The microscope is set to an overall magnification of 400x with an objective lens that has a focal length of 0.40 cm. The distance between the eyepiece and objective lenses is 12 cm. 1) Find the focal length of the eyepiece lens assuming a near point of 25 cm (the closest an object can be and still be seen in focus). Do not neglect any values in your calculation. (Express your answer to two significant figures.)
Answer:
[tex]f_{e}[/tex] = 1.9 cm
Explanation:
The magnification of a microscope is the product of the magnification of the eyepiece by the magnifier with the objective
M = M₀ [tex]m_{e}[/tex]
Where M₀ is the magnification of the objective and [tex]m_{e}[/tex] is the magnification of the eyepiece.
The eyepiece is focused to the near vision point (d = 25 cm)
[tex]m_{e}[/tex] = 25 / [tex]f_{e}[/tex]
The objective is focused on the distances of the tube (L)
M₀ = -L / f₀
Substituting
M = - L/f₀ 25/[tex]f_{e}[/tex]
1) Let's look for the focal length of the eyepiece (faith)
[tex]f_{e}[/tex] = - L 25 / f₀ M
M = 400X = -400
[tex]f_{e}[/tex] = - 12 25 /0.40 (-400)
[tex]f_{e}[/tex] = 1.875 cm
Let's approximate two significant figures
[tex]f_{e}[/tex] = 1.9 cm
Final answer:
The focal length of the eyepiece lens in the microscope is approximately -0.01 mm.
Explanation:
To find the focal length of the eyepiece lens, we can use the formula for the magnification of a compound microscope, which is given by:
M = -fobjective/feyepiece
Where M is the overall magnification, fobjective is the focal length of the objective lens, and feyepiece is the focal length of the eyepiece lens.
Given that the overall magnification is 400x and the focal length of the objective lens is 0.40 cm, we can rearrange the formula to solve for the focal length of the eyepiece lens:
feyepiece = -fobjective/M = -0.40 cm/400 = -0.001 cm = -0.01 mm.
Therefore, the focal length of the eyepiece lens is approximately -0.01 mm.
A light ray enters a glass enclosed fish tank. From air it enters the glass at 20.° with respect to the surface, then emerges into the water. The index for glass is 1.50 and for water 1.33.
(a) What is the angle of refraction in the glass?
(b) What is the angle of refraction in the water?
(c) Is there any incident angle in air for which the ray will not enter the water due to total internal reflection?
Answer:
a) [tex]\angle r_{ag}=38.79^{\circ}[/tex]
b) [tex]\angle r_{gw}=44.95^{\circ}[/tex]
c) not possible
Explanation:
Given:
angle of incidence on the air-glass interface, [tex]\angle i_{ag}=90-20=70^{\circ}[/tex]
refractive index of glass with respect to air, [tex]n_g=1.5[/tex]
refractive index of water with respect to air, [tex]n_a=1.33[/tex]
a)
For angle of refraction in glass we use Snell's law:
[tex]n_g=\frac{sin\ i_{ag}}{sin\ r{ag}}[/tex]
[tex]1.5=\frac{sin\ 70}{sin\ r_{ag}}[/tex]
[tex]\angle r_{ag}=38.79^{\circ}[/tex]
b)
Now we have angle of incident for glass-water interface, [tex]\angle i_{gw}=\angle r_{ag}=38.79^{\circ}[/tex]
And the refractive index of water with respect to glass:
[tex]n_{gw}=\frac{n_w}{n_g}[/tex]
[tex]n_{gw}=\frac{1.33}{1.5}[/tex]
[tex]n_{gw}=0.8867 [/tex]
Therefore, angle of refraction in the water:
[tex]n_{gw}=\frac{sin\ i_{gw}}{sin\ r_{gw}}[/tex]
[tex]0.8867 =\frac{sin\ 38.79}{sin\ r_{gw}}[/tex]
[tex]\angle r_{gw}=44.95^{\circ}[/tex]
c)
For total internal reflection through water the light must enter the glass-water interface at an angle greater than the critical angle.
So,
[tex]n_{gw}=\frac{sin\ i_{(gw)_c}}{sin\ 90}[/tex]
[tex]0.8867 =\frac{sin\ i_{(gw)_c}}{1}[/tex]
[tex]i_{(gw)_c}=62.46^{\circ}[/tex]
Now this angle will become angle of refraction for the air-glass interface.
Hence,
[tex]n_g=\frac{sin\ i_{ag}}{sin\ i_{(gw)_c}}[/tex]
[tex]1.5=\frac{sin\ i_{ag}}{0.8867 }[/tex]
[tex]sin\ i_{ag}=1.33005[/tex]
Since we do not have any angle for sine for which the value exceeds 1, therefore it is not possible that the light will reflect from the water.
Fluid flows over a smooth cylinder. The diameter of the cylinder is D and the length normal to the flow direction is L. The drag coefficient is defined as: The drag coefficient is essentially constant with a value of 1.1 in the range of Reynolds numbers of 103 to 105. In this range, at a velocity of 2 m/s the drag force is 3 N. When the velocity is doubled to 4 m/s the drag force is:
Answer:
Explanation:
Given
Coefficient of drag [tex]C_d=1.1[/tex]
Reynolds number [tex]Re.no.=103 to 105[/tex]
velocity [tex]v=2 m/s [/tex]
[tex]F_d=3 N[/tex]
if velocity if 2v i.e. [tex]4 m/s [/tex]
[tex]F_d=\frac{1}{2}C_d\rho A v^2----1[/tex]
keeping other factors as constant
[tex]F'_d=\frac{1}{2}C_d\rho A (2v)^2----2[/tex]
dividing 1 and 2
[tex]\frac{F_d}{F'_d}=\frac{v^2}{2v^2}[/tex]
[tex]F'_d=4F_d[/tex]
[tex]F'_d=4\times 3=12 N[/tex]
Twenty grams of a solid at 70°C is place in 100 grams of a fluid at 20°C. Thermal equilibrium is reached at 30°C.
The specific heat of the solid:
a. is equal to that of the fluid.
b. is less than that of the fluid.
c. is more than that of the fluid.
d. cannot be compared to that of a material in a different phase.
Answer:
c. is more than that of the fluid.
Explanation:
This problem is based on the conservation of energy and the concept of thermal equilibrium
[tex]heat= m s \Delta T [/tex]
m= mass
s= specific heat
\DeltaT=change in temperature
let s1= specific heat of solid and s2= specific heat of liquid
then
Heat lost by solid= [tex]20(s_1)(70-30)=800s_1 [/tex]
Heat gained by fluid=[tex]100(s_2)(30-20)=1000s_2 [/tex]
Now heat gained = heat lost
therefore,
1000 S_2=800 S_1
S_1=1.25 S_2
so the specific heat of solid is more than that of the fluid.
The correct option is:
(c) is more than that of the fluid.
Conservation of energy:
The conservation of energy suggests that the heat energy lost by the solid must be equal to the heat energy gained by the liquid.
Let the specific heat of the solid be [tex]s_s[/tex] and the specific heat of the liquid be [tex]s_l[/tex].
Heat energy lost by the solid is given by:
[tex]\Delta Q_s=ms_s\Delta T\\\\ \Delta Q_s=20s_s(70-30)\\\\ \Delta Q_s=800s_s[/tex]
Heat energy gained by the liquid:
[tex]\Delta Q_l=ms_l\Delta T\\\\ \Delta Q_l=100s_l(30-20)\\\\ \Delta Q_l=1000s_l[/tex]
According to the conservation of energy:
[tex]\Delta Q_s=\Delta Q_l\\\\800s_s=1000s_l\\\\\frac{s_s}{s_l}=\frac{1000}{800}\\\\\frac{s_s}{s_l}=\frac{5}{4}[/tex]
Hence, the specific heat of the solid is more than that of the fluid
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Consider the four quantum numbers of an electron in an atom, n, l, ml, and ms. The energy of an electron in an isolated atom depends on:______a. l, ml, and msonly.b. n only.c. n and l only.d. n, l, and mlonly.e. all four quantum numbers.
Answer:
The energy of an electron in an isolated atom depends on b. n only.
Explanation:
The quantum number n, known as the principal quantum number represents the relative overall energy of each orbital.
The sets of orbitals with the same n value are often referred to as an electron shell, in an isolated atom all electrons in a subshell have exactly the same level of energy.
The principal quantum number comes from the solution of the Schrödinger wave equation, which describes energy in eigenstates [tex]E_n[/tex], and for the case of an hydrogen atom we have:
[tex]E_n=-\cfrac{13.6}{n^2}\, eV[/tex]
Thus for each value of n we can describe the orbital and the energy corresponding to each electron on such orbital.
A cylinder with a piston contains 0.200 mol of oxygen at 2.00×105 Pa and 360 K . The oxygen may be treated as an ideal gas. The gas first expands isobarically to twice its original volume. It is then compressed isothermally back to its original volume, and finally it is cooled isochorically to its original pressure.Part AFind the work done by the gas during the initial expansion.W initial = JPart BFind the heat added to the gas during the initial expansion.Q initial = JPart CFind internal-energy change of the gas during the initial expansion.ΔU initial = JPart DFind the work done during the final cooling;W final = J
Answer:
A. [tex]W=600\ J[/tex]
B. [tex]Q=2112\ J[/tex]
C. [tex]\Delta U=1512\ J[/tex]
D. [tex]W=0\ J[/tex]
Explanation:
Given:
no. of moles of oxygen in the cylinder, [tex]n=0.2[/tex]initial pressure in the cylinder, [tex]P_i=2\times 10^5\ Pa[/tex]initial temperature of the gas in the cylinder, [tex]T_i=360\ K[/tex]According to the question the final volume becomes twice of the initial volume.
Using ideal gas law:
[tex]P.V=n.R.T[/tex]
[tex]2\times 10^5\times V_i=0.2\times 8.314\times 360[/tex]
[tex]V_i=0.003\ m^3[/tex]
A.
Work done by the gas during the initial isobaric expansion:
[tex]W=P.dV[/tex]
[tex]W=P_i\times (V_f-V_i)[/tex]
[tex]W=2\times 10^5\times (0.006-0.003)[/tex]
[tex]W=600\ J[/tex]
C.
we have the specific heat capacity of oxygen at constant pressure as:
[tex]c_v=21\ J.mol^{-1}.K^{-1}[/tex]
Now we apply Charles Law:
[tex]\frac{V_i}{T_i} =\frac{V_f}{T_f}[/tex]
[tex]\frac{0.003}{360} =\frac{0.006}{T_f}[/tex]
[tex]T_f=720\ K[/tex]
Now change in internal energy:
[tex]\Delta U=n.c_p.(T_f-T_i)[/tex]
[tex]\Delta U=0.2\times 21\times (720-360)[/tex]
[tex]\Delta U=1512\ J[/tex]
B.
Now heat added to the system:
[tex]Q=W+\Delta U[/tex]
[tex]Q=600+1512[/tex]
[tex]Q=2112\ J[/tex]
D.
Since during final cooling the process is isochoric (i.e. the volume does not changes). So,
[tex]W=0\ J[/tex]
PART ONE
A jet aircraft is traveling at 281 m/s in horizontal flight. The engine takes in air at a
rate of 107 kg/s and burns fuel at a rate of
4.23 kg/s. The exhaust gases are ejected at
679 m/s relative to the aircraft.
Find the thrust of the jet engine.
Answer in units of N.
PART TWO
Find the delivered power.
Answer in units of W
Answer:
1. F = 45,458.17 N
2. P = 12,800,000 W
Explanation:
Part 1. The thrust force is the sum of the forces on the air and on the fuel.
For the air, 107 kg of air is accelerated from 281 m/s to 679 m/s in 1 second.
F = ma
F = (107 kg) (679 m/s − 281 m/s) / (1 s)
F = 42,586 N
For the fuel, 4.23 kg of fuel is accelerated from 0 m/s to 679 m/s in 1 second.
F = ma
F = (4.23 kg) (679 m/s − 0 m/s) / (1 s)
F = 2,872.17 N
So the thrust on the jet is:
F = 42,586 N + 2,872.17 N
F = 45,458.17 N
Rounded to three significant figures, the force is 45,500 N.
Part 2. Power = work / time, and work = force × distance, so:
Power = force × distance / time
Power = force × velocity
P = (45,458.17 N) (281 m/s)
P = 12,773,745.77 W
Rounded to three significant figures, the power is 12,800,000 W.