Answer:
12.3 years
Explanation:
The equation of the radioactive decay can be written as follows:
[tex]\frac{N(t)}{N_0}=(\frac{1}{2})^{\frac{t}{\tau_{1/2}}}[/tex] (1)
where
N(t) is the amount of radioactive sample left at time t
N0 is the amount of radioactive sample at time t=0
t is the time passed
[tex]\tau_{1/2}[/tex] is the half-life of the isotope
The problem tells us that after t=36.9 y, the amount of sample which has become stable is 7/8. This means that 7/8 of the sample has already decayed, so the amount of radioactive sample left is
[tex]\frac{N(t)}{N_0}=1-\frac{7}{8}=\frac{1}{8}[/tex]
We can now re-arrange equation (1) by using this information and by substituting t=36.9 y we find:
[tex]\frac{t}{\tau_{1/2}}=log_{1/2} (\frac{N(t))}{N_0})\\\tau_{1/2}=\frac{t}{log_{1/2}(\frac{N(t)}{N_0})}=\frac{36.9 y}{log_{1/2}(1/8)}=\frac{36.9 y}{3}=12.3 y[/tex]
So, the answer is
12.3 years
Answer:
A. 12.3 years
Explanation:
Newton's 3rd law of motion states that "every action has an equal and opposite reaction." A golf ball was hit with force of 200 N forward. Explain how this relates to Newton's 3rd law of motion.
Special relativity cannot be used to study an object in which frame of reference
Special relativity can be used to study an object in which frame of reference ... C. A frame of reference that has a constant, positive acceleration.
The question is incomplete. The complete question is:
Special relativity cannot be used to study an object in which frame of reference?
A. A frame of reference that has no change in velocity
B. A frame of reference that is moving in a circle
C. A frame of reference that has a constant, positive acceleration
D. A frame of reference that has a constant, negative acceleration
Answer:
A frame of reference that has a constant, positive acceleration
A frame of reference that has a constant, negative acceleration
Explanation:
Special relativity applies to frames of reference in which an object is moving at constant velocity.
If the velocity is constant, it implies that acceleration will be zero hence options C and D will be correct since they both involve a non-zero change in velocity.
Lourdes mixes several ingredients in a bowl, creating a cake batter. She holds the bowl up and turns it upside down, causing the cake batter to slowly fall into a pan. As the cake batter falls into the pan, Lourdes also uses a spatula to scrape the cake batter from the sides of the bowl and into the pan.
What forces are acting on the cake batter as it moves from the bowl to the pan? Be sure to explain whether each force acting on the batter is a contact force or a noncontact force. You should also explain how each force affects the motion of the cake batter.
friction and gravity ....................
The motion of the cake batter from the bowl to the pan is influenced by gravitational force (noncontact), normal force (contact by the spatula), and adhesive force (contact with the bowl). These forces affect how the batter moves and is transferred into the pan.
When Lourdes mixes the cake batter and transfers it from the bowl to the pan, several forces are in play affecting its motion. These include:
Gravitational force: This noncontact force pulls the cake batter downwards into the pan. It is a consistent force acting on all objects on Earth and depends on the mass of the batter.Normal force: As Lourdes uses a spatula to scrape the batter, the spatula exerts a contact force against the sides of the bowl, helping to dislodge the batter and move it towards the pan.Adhesive force: This contact force explains the batter's tendency to stick to the sides of the bowl and the spatula, opposing the motion towards the pan.Each force mentioned influences the flow and transfer of the cake batter, whether it is through contact, like the normal and adhesive forces, or from a distance, such as the gravitational force.
Acceleration of an 82 kg couch that is pushed across the floor with an unbalanced force of 21N
According to Newton's principle two
F=m*a=>a=F/m=21/82=0.25 m/s²
A ray of light is incident on a plane mirror at an angle of 40 degrees with the mirror surface. What will be the angle of reflection?
a) 40 degrees
b) 50 degrees
c) 90 degrees
d) 150 degrees
b) 50 degrees
incident angle = reflected angle BUT grazing angle is given as 40 so incident angle taken from the normal at right angles to the mirror is 50
a) 40 degrees
When a light wave reflects off a mirror, it must obey the
law of reflection - angle of incidence is equal to angle of reflection.
If the angle of incidence is 40 degrees, the angle of reflection is 40
A student throws a baseball upwards at an angle of 60 degrees to the horizontal. The initial horizontal and vertical components are 12.5 m/s and 21.7 m/s, respectively.
Given data
ball throws upwards at an angle 60°
Horizontal component (Vh) = 12.5 m/s,
Vertical component (Vv) = 21.7 m/s ,
The magnitude of throw/resultant velocity (V) = ?
The resultant velocity /the velocity with which ball is throws is determined by the following equation
V = √[(Vh)² + (Vv)²]
= √[(12.5)² + (21.7)²]
= 25.04 m/s
The resultant velocity or the velocity with which the ball is thrown is 25 m/s
Answer:
d
Explanation:
The acceleration stays the same. Velocity is the one that changes.
20 pts easy question
Which question could Not be answered by using the scientific method?
Do girls grow faster than boys?
Does this shirt look bad?
Is cooked meat better for a dog than dog food?
Which US city gets the most rain?
which player is usually the best ball-handler on the court?
A. shooting guard
B. small forward
C. power forward
D. point guard
I think it's D)!!!!!!!!!!
I would think after watching 3 basket ball games the point gaurd.
Constructive interference occurs when the crests of one wave overlap the crests of another wave. What is the result of constructive interference? A. decreased frequency B. increased frequency C. decreased amplitude D. increased amplitude
Answer:
D.
hope this helps
A train is approaching a signal tower at a speed of 40m/s. The train engineer sounds the 1000-Hz whistle, while a switchman in the tower responds by sounding 1200-Hz siren. THe air still and the speed is 340m/s. What is the frequency of the train whistle tone that is heard by the switchman?
300/340x1000Hz
380/340x1000Hz
340/300x1000Hz
1000Hz
340/380x1000Hz
v = speed of the source of sound or the train towards the listener or switchman = 40 m/s
V = actual speed of sound = 340 m/s
f = actual frequency of sound as emitted from source or the train = 1000 Hz
f' = frequency as observed by the listener or by switchman = ?
Using Doppler's law , frequency observed by a listener from a source moving towards it is given as
f' = V f /(V - v)
inserting the values
f' = 340 x 1000 /(340 - 40)
f' = 340 x 1000/300
The frequency of the train whistle heard by the switchman, calculated using the Doppler effect, is 380/300 x 1000 Hz.
Explanation:To determine the frequency of the train whistle heard by the switchman, we use the Doppler effect formula for sound moving towards a stationary observer. Since the speed of the train is less than the speed of sound, the formula to calculate the frequency received (f') is given by f' = f ((v + v0)/(v - vs)), where f is the source frequency, v is the speed of sound, v0 is the velocity of the observer (0 m/s since the observer is stationary), and vs is the velocity of the source. Plugging in the given values, we get:
f' = 1000 Hz ((340 m/s + 0 m/s) / (340 m/s - 40 m/s)) = 1000 Hz (380 m/s / 300 m/s) = 380/300 x 1000 Hz
So, the correct frequency of the train whistle tone heard by the switchman is 380/300 x 1000 Hz.
A motor having a maximum power rating of 8.1 x 104 watts is used to operate an elevator with a weight of 1.8 x 104 newtons. What is the maximum weight this motor can lift at an average speed of 3.0 meters per second?
If the power rating of the motor is 8x10^4 Watts and our equation for Power is:
[tex]Power=\frac{Energy}{time}=\frac{Work}{time}=\frac{Force \times Displacement}{time}\\\\P=Force \times Velocity[/tex]
Note that:
[tex]F=ma=mg[/tex]
where g is the average gravity on Earth which is approximately 9.8 m/s^2.
And so:
[tex]P=F \times V\\P=m \times g \times V\\\\\ m=\frac{P}{gv} \\\\[/tex]
[tex]m=\frac{8.1 \times 10^4 }{9.8 \times 3} =2755.1kg[/tex]
In terms of force:
[tex]F=mg=2755.1kg \times 9.8 \frac{m}{s^2}=27000N[/tex]
The maximum weight of motor that can lifted at the given speed is of 27000 N.
Given data:
The maximum power rating of the motor is, [tex]P = 8.1 \times 10^{4} \;\rm W[/tex].
The weight of elevator is, [tex]W = 1.8 \times 10^{4} \;\rm N[/tex].
The speed of motor is, v = 3.0 m/s.
Since, the power rating of motor is obtained due to the force experienced on the elevator. Then,
[tex]P = F \times v[/tex]
Solving as,
[tex]8.1 \times 10^{4} = F \times 3.0 \\F = 27000 \;\rm N[/tex]
Now, the force experienced on the elevator is due to the weight of motor. Then,
Force (F) = Weight of motor (W')
[tex]27000 = W' \\\\W' = 27000 \;\rm N[/tex]
Thus, we can conclude that the maximum weight of motor that can lifted at the given speed is of 27000 N.
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The curved section of a horizontal highway is a circular unbanked arc of radius 740m. If the coefficient of static friction between this roadway and typical tires is .40, what would be the maximum safe driving speed for this horizontal curved section of highway
The maximum speed at which the car makes the turn without slipping is [tex]\boxed{54\,{{\text{m}} \mathord{\left/{\vphantom {{\text{m}} {\text{s}}}} \right.\kern-\nulldelimiterspace} {\text{s}}}}[/tex].
Further Explanation:
Given:
The coefficient of static fiction between the road and tyres is [tex]0.40[/tex].
The radius of curvature of the road is [tex]740\,{\text{m}}[/tex].
Concept:
As the car turn around the curved road, the centripetal force acting on the car should be balanced by the friction force acting on the car to avoid the slipping of the car on the road.
Write the force balancing equation for the forces acting on the car.
[tex]{F_{centripetal}} = {F_{frcition}}[/tex] …… (I)
The centripetal force acting on the car is given by.
[tex]{F_{centripetal}} = \dfrac{{m{v^2}}}{r}[/tex]
Here, [tex]m[/tex] is the mass of the car, [tex]v[/tex] is the velocity of the car and [tex]r[/tex] is the radius of the curvature of path.
The friction force acting on the car is given by.
[tex]{F_{fricton}} = \mu mg[/tex]
Here, [tex]\mu[/tex] is the static friction coefficient and [tex]g[/tex] is the acceleration due to gravity.
Substitute [tex]\dfrac{{m{v^2}}}{r}[/tex] for [tex]{F_{centripetal}}[/tex] and [tex]\mu mg[/tex] for [tex]{F_{friction}}[/tex] in equation (I).
[tex]\begin{aligned}\frac{{m{v^2}}}{r} &= \mu mg\\ v&= \sqrt {\mu rg}\\\end{aligned}[/tex]
Substitute the values in the above expression.
[tex]\begin{aligned}v&= \sqrt {0.40 \times 740 \times 9.8}\\ &= \sqrt {2900.8}\\ &= 53.85\,{{\text{m}} \mathord{\left/{\vphantom {{\text{m}} {\text{s}}}} \right.\kern-\nulldelimiterspace} {\text{s}}}\\&\approx 54\,{{\text{m}}\mathord{\left/{\vphantom {{\text{m}} {\text{s}}}} \right.\kern-\nulldelimiterspace} {\text{s}}}\\\end{aligned}[/tex]
Thus, the maximum speed at which the car makes the turn without slipping is [tex]\boxed{54\,{{\text{m}} \mathord{\left/{\vphantom {{\text{m}} {\text{s}}}} \right.\kern-\nulldelimiterspace} {\text{s}}}}[/tex].
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Answer Details:
Grade: High School
Chapter: Circular motion
Subject: Physics
Keywords: Curved section, circular, unbanked road, static friction, maximum safe driving, radius 740m, without slipping, centripetal force, friction force.
Suppose a 48-N sled is resting on packed snow. The coefficient of kinetic friction is 0.10. If a person weighing 660 N sits on the sled, what force is needed to pull the sled across the snow at constant speed?
Assume the snow is uniform, and horizontal.
Given:
coefficient of kinetic friction = 0.10 = muK
weight of sled = 48 N
weight of rider = 660 N
normal force on of sled with rider = 48+660 N = 708 N = N
Force required to maintain a uniform speed
= coefficient of kinetic friction * normal force
= muK * N
= 0.10 * 708 N
=70.8 N
Note: it takes more than 70.8 N to start the sled in motion, because static friction is in general greater than kinetic friction.
1) A piano tuner is testing a wire currently under 2000 N tension. The wire is 1.5 m long and has a mass of 20 g. If the tuner's computer can detect a maximum frequency of 10,000 Hz, what is the highest harmonic number the computer can detect (1 point)
A) 77
B) 100
C) 25
D) 63
2) A wave is traveling with a speed of 400 m/s and it has a wavelength of 28 m. What will the frequency of the wave be if the wavelength is doubled but the speed remains the same? (1 point)
A) 9.09 Hz
B) 14.3 Hz
C) 21.7 Hz
D) 7.14 Hz
3) If a standing wave is vibrating in it's third harmonic, how many nodes does it have? (1 point)
A) 4
B) 3
C) 2
D) 1
4) An organ pipe, which is a pipe closed at one end, is 2.46 m long and the speed of sound in air in that pipe is 345 m/s. What is the frequency of the fundamental harmonic in this pipe? (1 point)
A) 44.9 Hz
B) 20.6 Hz
C) 35.1 Hz
D) 13.2 Hz
5) Using the same organ pipe from question 11, how many possible harmonics are there in the normal human hearing range of 20 Hz to 20,000 Hz? (1 point)
A) 570
B) 985
C) 101
D) 47
6) A standing wave is set up on a violin string to produce a note of A sharp Contra (58 Hz). The violin string is 32 cm long. If the sound is produced in the fundamental frequency, what is the speed of the wave moving across the string? (1 point)
A) 52.78 m/s
B) 18.83 m/s
C) 20.01 m/s
D) 37.12 m/s
1.
Answer:
N = 77
Explanation:
1) As we know that Tension in the wire is given as
T = 2000 N
now mass per unit length of the wire is given as
[tex]\frac{m}{L} = \frac{20 \times 10^{-3} kg}{1.5 m}[/tex]
[tex]\frac{m}{L} = 0.013 kg/m[/tex]
Now fundamental frequency is given as
[tex]f_o = \frac{1}{2L}\sqrt{\frac{T}{m/L}}[/tex]
[tex]f_o = \frac{1}{2\times 1.5}\sqrt{\frac{2000}{0.013}}[/tex]
[tex]f_o = 129 Hz[/tex]
now highest frequency is given as 10000 Hz
so total harmonics is given as
[tex]N = \frac{10000}{129}[/tex]
[tex]N = 77 [/tex]
2.
Answer:
D) 7.14 Hz
Explanation:
As we know that
speed = (frequency)(wavelength)
given that
speed = 400 m/s
wavelength = 28 m
so frequency is given as
[tex]f = \frac{400}{28}[/tex]
[tex]f = 14.3 Hz[/tex]
now if wavelength is doubled then we will have
[tex]wavelength = 56 m[/tex]
new frequency will be
[tex]f = \frac{400}{56}[/tex]
[tex]f = 7.14 hz[/tex]
3.
Answer:
Number of nodes = 4
A) 4
Explanation:
Number of nodes = number of harmonics + 1
so here we know that
number of harmonics = 3
Number of nodes = 3 + 1
Number of nodes = 4
4.
Answer:
C) 35.1 Hz
Explanation:
fundamental frequency in an organ pipe closed at one end is given as
[tex]f = \frac{v}{4L}[/tex]
here we know that
v = 345 m/s
L = 2.46 m
now we have
[tex]f = \frac{345}{4(2.46)}[/tex]
[tex]f = 35.1 Hz[/tex]
5.
Answer:
A) 570
Explanation:
Number of harmonics is given as
[tex]N = \frac{maximum :\frequency}{fundamental\: frequency}[/tex]
[tex]N = \frac{20,000}{35.1}[/tex]
[tex]N = 570[/tex]
6.
Answer:
[tex]v = 37.12 m/s[/tex]
Explanation:
For fundamental frequency we know that
[tex]f_o = \frac{v}{2L}[/tex]
here we know that
[tex]f_o = 58 Hz[/tex]
[tex]L = 32 cm[/tex]
now we have
[tex]58 = \frac{v}{2(0.32)}[/tex]
[tex]v = 37.12 m/s[/tex]
Suppose you want to separate the leaves, acorns, and twigs from a pile of soil. Filtration and distillation are two processes of separating mixtures. Explain which process you would use and why.
Have only 30 minutes to answer!!!!!
I will mark brainliest!
Mark him brainliest! XD
(your welcome btw)
A player throws a football 50.0 m at 61.0° north of west. what is the westward component of the displacement of the football?
Answer: 24.24 m
Explanation:
A player throws football 50.0 m at 61° North of west. we will write this in terms of horizontal and vertical components.
Horizontal component: 50 cos 61° = 24.24 m which is westwards
Vertical component: 50 sin 61° = 43.73 m which towards North.
Refer to diagram below.
Thus, the westward component of displacement of the football is the horizontal component of the displacement = 24.24 m.
The westward displacement of the football that was thrown by a player 61.0° north of west can be calculated using trigonometry. Specifically, by multiplying the total displacement (50.0 m) with the cosine of the angle (61.0°), resulting in a westward displacement of approximately 25.5 m.
Explanation:The student's question concerns the westward displacement of a football thrown by a player at a direction 61.0° north of west. This displacement is a component of the total displacement of the football. Since the direction is specified relative to west, the western component or the westward displacement can be calculated using basic trigonometry.
In this case, the westward displacement is the adjacent side of the triangle formed with the displacement as hypotenuse and the angle being 61.0°. Hence, the westward component can be calculated using cosine of the angle times the hypotenuse, which is 50.0 m. We can calculate it as follows:
Westward displacement = 50.0 m * cos(61.0°)
Using a calculator, this gives a westward displacement of approximately 25.5 m, after rounding to one decimal place. Thus, the football was displaced approximately 25.5 m to the west.
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A person walks one mile every day for exercise, leaving her front porch at 9:00 a.M. And returning to her front porch at 9:25 a.M. What is the total displacement of her daily walk
Final answer:
The total displacement of the person's daily walk, starting and ending at the same front porch, is zero, as displacement considers only the initial and final positions.
Explanation:
The question pertains to the concept of displacement in physics, which is different from distance. Displacement is a vector quantity that only considers the initial and final position of an object, ignoring the path taken. In the case of a person who walks one mile every day for exercise, starting from her front porch at 9:00 AM and returning to the same spot at 9:25 AM, her total displacement is zero. This is because her final position (the front porch) is the same as her initial position, meaning there has been no change in position regardless of the distance walked.
Which of the following describes an object in static equilibrium?
A.A platypus lies motionless on the sand.
B.A tuna speeds up from 2 m/s to 3 m/s
C.A dolphin jumps out of the water
D.A zebra shark swims at a constant speed of 8 m/s
Answer:
Option A is the correct answer.
Explanation:
Static equilibrium means an object object is at rest and is in a state of equilibrium.
If we examine options B, C and D we can see that, in each case object is in a state of motion.
B) Tuna is in a motion.
C) Dolphin is a motion.
D) Zebra is a motion
In option A platypus lies motionless on the sand, which is an example of static equilibrium.
so, option A is the correct answer.
The number of slices of pepperoni needed by a pizza restaurant is given by the equation p = 14n. In this equation, n is the number of pizzas the restaurant will make. How many slices of pepperoni are needed to make 40 pizzas?
A. 14
B. 560
C. 54
D. 40
If N is the number of pizza’s the restraunt will make and the equation tells us that the restraunt will make 40 pizza’s, I believe this turns the equation into p=14(40).
Answer:
The slices of pepperoni are 560.
Explanation:
The equation is given by
[tex]p=14 n[/tex]
We need to calculate the slices of pepperoni are needed to make 40 pizzas
Using given equation
[tex]p=14n[/tex]
Where, p = number of slices
n = number of pizza
Put the value of n in the equation
[tex]p = 14\times40[/tex]
[tex]p=560[/tex]
Hence, The slices of pepperoni are 560.
PLEASE HELP!!
Describe how standing waves are created when you have a rope attached to a point on a wall.
Answer
standing waves are created when you have a rope attached to a point By moving your hand up and down we can create waves, and as we know that our rope is attached to a point on a wall, which means it has boundary. The waves will reflect back and interface with new waves and this is how standing waves are created.
hope this will help.
Answer:
Please see the explanation
Explanation:
As we know that standing waves have nodes and anti nodes which is produced by repeated interference of two waves of same frequency in opposite direction in the same medium. In this case when we have a rope attached to a point on a wall, we move the rope in up and down direction we will create waves.
The wave will go up to the wall and then reflect back and thus create an opposite wave. And as we can create a standing wave.
Ball a of mass 5.0 kilograms moving at 20 meters per second collides with ball b of unknown mass moving at 10 meters per second in the same direction. after the collision, ball a moves at 10 meters per second and ball b at 15 meters per second, both still in the same direction. what is the mass of ball b? * 1 point your answer
Answer:
10.0 kg
Explanation:
The problem can be solved by applying the law of conservation of momentum - the total momentum before the collision must be equal to the total momentum after the collision:
[tex]p_i = p_f\\m_A u_A + m_B u_B = m_A v_A + m_B v_B[/tex]
where:
[tex]m_A = 5.0 kg[/tex] is the mass of ball A
[tex]u_A = +20 m/s[/tex] is the velocity of ball A before the collision
[tex]m_B = ?[/tex] is the mass of ball B
[tex]u_B = +10 m/s[/tex] is the velocity of ball B before the collision (same sign of uA, since they are moving in same direction)
[tex]v_A = +10 m/s[/tex] is the velocity of ball A after collision
[tex]v_B = +15 m/s[/tex] is the velocity of ball B after collision
Re-arranging the equation, we can solve to find mB, the mass of ball B:
[tex]m_B u_B - m_B v_B = m_A v_A - m_A u_A\\m_B = \frac{m_A (v_A -u_A)}{u_B -v_B}=\frac{(5.0 kg)(10 m/s-20 m/s)}{10 m/s-15 m/s}=10.0 kg[/tex]
Pyrite is called "fool's gold" because it's looks a lot like gold. Which properties can be used to tell gold and pyrite apart?
Answer:
On the basis of physical and chemical properties, pyrite can be differentiated from real gold.
Explanation:
Some properties which can be used to differentiate pyrite from real gold are given below:
i) Real gold is made of same kind of atoms while pyrite is made of combinations of atoms like Iron and Sulphur.
ii) Pyrite is lighter in color than real gold.
iii) When we heat pyrite and real gold, both show different colors at higher temperatures.
iv) Pyrite is less dense and harder than real gold.
v) Real gold has weight 1.5 times than that of pyrite.
Which of the following is an abiotic limiting factor for a plant population in an ecosystem?
Invasive weed species
Seed dispersal by wind
Availability of soil minerals
Disease-causing fungal spores
Correct answer is Availability of soil minerals.
There are two types of limiting factors that affect plant population in a ecosystem. They are:
BioticAbioticBiotic factors includes food, diseases etc. Such as Invasive weed species, seed dispersal by wind, disease-causing fungal spores are examples of biotic limiting factor.
Abiotic factors include sunlight, temperature and chemical environment. The availability of soil mineral is an example of abiotic limiting factor. Growth of plant population depends on availability of soil minerals.
In the context of an ecosystem, an abiotic limiting factor refers to non-living elements that may limit a plant's survival or growth. Among the options provided, 'Availability of soil minerals' serves as an abiotic limiting factor.
Explanation:The question asks for an abiotic limiting factor, which refers to non-living aspects of an ecosystem that could limit a plant's growth or survival. In this case, the correct answer would be 'Availability of soil minerals.' Soil minerals are considered abiotic because they are non-living elements of the environment. They can limit plant growth if they are in short supply, as plants require specific minerals to carry out various biological functions. For example, nitrogen is a critical soil mineral that plants use to produce proteins and DNA.
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15 POINTS !!!
1. Which of the following statements is correct for the work-kinetic energy theorem?
Wnet= change in potential energy
Wnet= change in kinetic energy
Wnet= change in elastic potential energy
Wnet= change in total energy
2. In which of the following cases is the torque greater? (see attachment)
3.
When a car makes a sharp left turn, what causes the passenger to move toward the right side of the car?
inertia
centripetal force
centrifugal force
centripetal acceleration
4. A 0.5 kg ball rolls down a frictionless inclined plane. The height of the inclined plane is 0.5m. What is the kinetic energy of the ball when it reaches the bottom of the inclined plane?
9.8 J
4.9 J
2.5 J
0.3 J
#1
As per work energy theorem work done by all forces must be equal to change in its kinetic energy
so correct answer will be
[tex]W_{net} [/tex] = change in kinetic energy
#2
Torque is defined as
[tex]\tau = r \times F[/tex]
[tex]\tau = rFsin\theta[/tex]
so here torque will be maximum when applied force is perpendicular to the rod
so first figure of rod is correct for maximum torque
#3
When car makes turn then its passengers moves outwards which is due to the property of inertia because due to this property passengers has tendency to move in same direction and hence it feels to move outwards
So correct answer will be
inertia
#4
As per energy conservation we can say
initial potential energy = final kinetic energy
[tex]PE = KE[/tex]
[tex]KE = mgH[/tex]
[tex]KE = 0.5(9.8)(0.5)[/tex]
[tex]KE = 2.5 J[/tex]
How do two objects at different temperatures attain thermal equilibrium?
A.As the two objects touch, thermal energy flows from the colder block to the warmer block until both blocks have the same amount of heat energy and kinetic energy.
B.As the two objects touch, thermal energy flows as heat from surrounding air until particles in both blocks become stationary and reach the same temperature.
C.As the two objects touch, thermal energy flows as heat from the warmer block to the colder block until particles in both blocks move at the same rate and reach the same temperature.
D.As the two objects touch, kinetic energy flows as heat from the warmer block to the colder block until both blocks reach the same temperature and have the same thermal energy.
Answer:
C.As the two objects touch, thermal energy flows as heat from the warmer block to the colder block until particles in both blocks move at the same rate and reach the same temperature.
Explanation:
Heat is the transfer of thermal energy from an object at higher temperature to an object at colder temperature.
The temperature of an object is a measure of how fast the particles in the object move: the higher its temperature, the faster the particles move, the higher the average kinetic energy of the particles in the object. As a result, the particles of the object at higher temperature tend to transfer more energy (called thermal energy) to the particles of the object at colder temperature by colliding with them: this process continues until the particles of the colder object reach the same average kinetic energy as the particles of the warmer object, and this means that the two objects have reached the same temperature.
When density increases, what happens to the number of molecules in a volume of air?
When density increases the number of molecules stay the same, im not entirely sure but i hope its right.
A student performs a reaction twice. In the second trial, she raises the temperature by 20¨¬C and notices that the reaction takes place more quickly. She concludes that the reaction must be endothermic. Explain why the student is incorrect.
Answer: She is incorrect to conclude that the reaction is endothermic.
As in the second trial, the temperature has increased by 20 °C , that means the heat has been released and energy is released in exothermic reactions.
Exothermic reactions: The reactions in which the energy of the products is less than the energy of the reactants, and the excess energy is released as heat.
Endothermic reactions: The reactions in which the energy of the products is more than the energy of the reactants, and the excess energy is absorbed as heat.
Explanation:
An endothermic reaction is a reaction in which the reactants absorb energy and the energy of products is more than that of reactants.
Whereas an exothermic reaction is a reaction in which the reactants have more energy as compared to products. Hence, there will be release of energy.
Therefore, when temperature is increased by [tex]20^{o}C[/tex] then it means we are providing more energy to the reactants. As a result, there will be release of energy. Hence, the reaction will be exothermic in nature and not endothermic.
Thus, we can conclude that the student is incorrect because the reaction is exothermic and not endothermic.
*Physical Science* *E2020* *Unit Test*
Four students were loading boxes of food collected during a food drive. The force that each student exerted while lifting and the distance each box was lifted are listed in the table.
| Student | Force(N) | Distance(m) |
|-------------------|--------------------------|--------------------------|
| Chet | 50 | 1.0 |
|-------------------|--------------------------|--------------------------|
| Mika | 40 | 2.0 |
|-------------------|--------------------------|--------------------------|
| Sara | 30 | 1.5 |
|-------------------|--------------------------|--------------------------|
| Bill | 60 | 0.5 |
|__________|______________|_____________ |
Which lists the students in order from the greatest amount of work done to the least? (Work: W = Fd)
A. Bill, Sara, Chet, Mika
B. Mika, Chet, Sara, Bill
C. Bill, Chet, Mika, Sara
D. Mika, Sara, Chet, Bill
i think its b
hope this helps
Answer:The correct answer is option B.
Explanation:
Work done is defined product of force applied on an object and the displacement of an object on applying of force.It is measured in Joules.
[tex]W=Force\times Displacement[/tex]
1. Chet
Work done = [tex]50 N\times 1.0 m= 50.0 Joules[/tex]
2. Mika
Work done = [tex]40 N\times 2.0 m= 80.0 Joules[/tex]
3. Sara
Work done = [tex]30 N\times 1.5 m= 45.0 Joules[/tex]
4.Bill
Work done = [tex]60 N\times 0.5 m= 30.0 Joules[/tex]
The greatest work was done by Mika and least work was done by BIll. The order from the greatest amount of work done to the least.
Mika>Chet>Sara>Bill.
Hence ,the correct answer is option B.
Some life forms move so slowly that their movement can not be detected by normal observation the best way to determine any movement is by placing a mark at some point, and observing any change in position from it. Why is this true
because the form can be watched over a long time for deviations from the mark.
like fingernails, the grow slowly too. after a time, they get clipped
Gino made a table to describe parts of the electromagnetic spectrum.
What mistake did Gino make?
X-rays should have a low frequency and a long wavelength.
Infrared light should have a high frequency, not a low frequency.
Radio waves should have a very high frequency and a very short wavelength.
Ultraviolet light should have a short wavelength, not a long wavelength.
Answer: Ultraviolet light should have a short wavelength, not a long wavelength.
Explanation:
Relation between the frequency and wavelength if given by:
[tex]\nu=\frac{c}{\lambda }[/tex]
[tex]\nu=\text{frequency of electromagnetic wave}[/tex]
[tex]\lambda =\text{wavelength of an electromagnetic wave}[/tex]
[tex]c=\text{speed of light}=3\times 10^{8} m/s[/tex]
From the above relation we can say that frequency and wavelength are inversely related to each other.
[tex]\nu\propto\frac{1}{\lambda }[/tex]
From the Gino's table, the mistake made by her was , instead of writing low wavelength for Ultraviolet rays she wrote long. Since the ultraviolet rays have higher frequency they have low value wavelength.