Scientists should not repeat experiments to see if their data is reproducible.
True or False?

Answer:

D. Ultraviolet light

Explanation:

Edge 2021

If the ratio of red to blue marbles in a bag is 3 : 2 . If there are 18 red marbles, then there are 12 marbles in the bag.

It is the relative value that represents the hundredth part of any number for example 2% of any number represents, 2 multiplied by the 1/100th of that number.

As given in the problem, the  ratio of red to blue marbles in a bag is 3:2. If there are 18 red marbles, then we have to find the number of blue marbles,

The number of the blue marbles = 18 × 2 / 3

                                                     = 12

Thus, If the ratio of red to blue marbles in a bag is 3 : 2 . If there are 18 red marbles, then there are 12 marbles in the bag.

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The terminal speed of the skydiver falling feet first is 53.2 m/s.

To find the terminal speed of the skydiver, we can use the formula:

vt = sqrt((2 * m * g) / (ρ * A * Cd))

where:

Using the given values, we can plug them into the formula:

vt = sqrt((2 * 72 kg * 9.8 m/s2) / (1.2 kg/m3 * (0.21 m * 0.41 m) * 0.80))

vt = 53.2 m/s

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The terminal speed of a 72 kg skydiver falling feet first is approximately 189.25 m/s. This is calculated using the formula for terminal velocity, with given values for mass, air density, cross-sectional area, and drag coefficient. The cross-sectional area was determined based on the dimensions of the skydiver.

To find the terminal speed ([tex]v_t[/tex]) of the skydiver, we use the formula for terminal velocity:

[tex]v_t[/tex] = √(2mg / ρA[tex]C_d[/tex])

Where:

m = 72 kg (mass of the skydiver)

g = 9.8 m/s² (acceleration due to gravity)

ρ = 1.2 kg/m³ (density of air)

A = 0.041 m² (cross-sectional area in meters squared, which is 0.21 m * 0.41 m)

[tex]C_d[/tex] = 0.80 (drag coefficient)

Putting the values into the formula:

[tex]v_t[/tex] = √((2 * 72 kg * 9.8 m/s²) / (1.2 kg/m³ * 0.041 m² * 0.80))

[tex]v_t[/tex] = √(1411.2 / 0.03936)

[tex]v_t[/tex] = √(35848.78)

[tex]v_t[/tex] ≈ 189.25 m/s

Therefore, the terminal speed of the skydiver falling feet first is approximately 189.25 m/s.

An unbalanced force is needed to change its speed or direction. So, option B.

Newton's first law states that, an object will continue its state of rest or uniform motion, unless it is acted upon by an external force.

Here,

The object is said to be moving at a constant speed in one direction. So, a force is required to change the speed or direction of its movement.

Depending upon the mass, an object can be slowed down or accelerated by a force. A force has the power to alter the motion of an object. An object will move differently when subjected to a greater force. In order to experience the same change in motion, a heavier item needs to be subjected to a greater force than a lighter object.

The velocity of an object will alter as a result of unbalanced forces. The object has the ability to alter its speed, direction, or both. An object's velocity changes as a result of unbalanced forces acting on it, which provide a net force.

Hence,

An unbalanced force is needed to change its speed or direction. So, option B.

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The acceleration of a skydiver when air resistance is 86% of her weight is calculated by finding the net force on her (weight minus air resistance), then dividing this by her mass. The result is 1.4 m/s^2, reflecting the balance of forces and the concept of terminal velocity.

To calculate the acceleration of a skydiver when the air resistance is 86% of her weight, we must first understand that the net force on the skydiver is her weight minus the force of air resistance. If the air resistance is 86% of the skydiver's weight, then only 14% of her weight is acting downwards. Considering the weight (force) is the mass (m) times the acceleration due to gravity (g), or F=mg. We then have, a = Fnet / m = 0.14 * weight / m = 0.14 * g (as weight = mg).

Given g (acceleration due to gravity) is 10 m/s2, substituting this into our equation gives an acceleration of a = 0.14 * 10 m/s2, which is 1.4 m/s2. Therefore, the acceleration of the skydiver when air resistance builds up to 86% of her weight is 1.4 m/s2.

It's important not only to understand formulae in physics but also the concepts they express. In this situation, that concept is the balance of forces and how they affect an object's movement. In the case of a skydiver, as they fall, air resistance builds up until it equals their weight, causing their acceleration to decrease until they reach a constant velocity, known as 'terminal velocity'.

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The sun is 900,000 miles (1,448,410 km) wide. It is the brightest object in the sky. To put into perspective how big the sun is, about 1.4 million Earths could fit inside the sun!

The speed of the water will be "43.75 ft/sec".

According to the question,

Initially inner diameter,

Final diameter,

By continuity equation, we get

→ [tex]Area1\times Velocity1=Area2\times Velocity2[/tex]

By substituting the values, we get

→ [tex]pi\times (\frac{0.052}{2} )^2\times 7= pi\times (\frac{0.0208}{2} )^2\times Velocity[/tex]

→             [tex]Velocity = 43.75 \ ft/sec[/tex] (speed)

Thus the above answer is correct.

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Answer:

13608 joules

Explanation:

We are given that mass of scooter=84 kg

Speed of scooter=18 m/s

We have to calculate the kinetic energy

We know that formula of kinetic energy

[tex]K.E=\frac{1}{2}mv^2[/tex]

Substitute the values then we get

K.E=[tex]\frac{1}{2}\times 84\times (18)^2=13608 joules[/tex]

Hence, the kinetic energy of an scooter=13608 joules

Increasing temperature in lava leads to an increase in its thermal energy, causing more vigorous molecular motion and keeping the lava in a liquid state for a longer period. Cooling of the lava involves energy transfer to its surroundings by radiation and conduction, with notable effects such as steam production when lava encounters colder matter.

As the temperature of lava increases, the thermal energy content of the lava also increases. This increase in thermal energy causes the vibrational motions within the material to become more vigorous. As a result, when we consider the formation of igneous rock, lava that has a higher temperature will remain in a liquid state for a longer period before it cools and freezes into solid rock. The physical processes associated with a large body of cooling lava involve the transfer of energy through radiation and conduction. Specifically, the rate of energy transfer by radiation from the surface of lava into the surroundings can be calculated using the difference in temperature between the lava's surface, its interior, and the surrounding environment.

The scenario detailed here, with lava cooling from 1200°C in the interior to 450°C at the surface, highlights how heat dissipates from the hotter to the colder areas. The process is analogous to when lava flows into cold ocean water, transferring heat so rapidly that steam is produced. Therefore, as lava temperatures increase, the lava will continue to behave as a hotter substance, capable of transferring high amounts of energy to cooler surrounding areas until an equilibrium is reached.

Answer:

velocity

Explanation:

The relation between wave velocity, frequency and wavelength of a wave is given by

wave velocity = frequency x wavelength

So, as the frequency and wavelength is given we can find the wave velocity.

Answer:

10

Explanation:

The glucose molecules produce the energy currency ATP by the process of glycolysis. If one molecules of glucose makes 30 molecules of ATP, then 10 glucose molecules are needed to make 300 molecules of ATP in aerobic respiration.

Glycolysis is the process of breakdown of glucose to produce the chemical energy in the form of ATP i.e. Adenosine triphosphate. Glycolysis is called the cellular respiration where the oxygen and glucose is consumed to produce ATP and carbon dioxide.

Body stores the chemical energy in the form of glucose, when body needs energy, these glucose molecules are broken down to produce ATP.

If one molecule of ATP produces 30 ATP molecules, then, the number of glucose molecules needed to produce 300 ATP molecules is:

= (300 /30) = 10

Therefore 10 glucose molecules are needed to produce 300 ATP molecules.

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To calculate the car's acceleration, we convert the initial speed of 60 mph to 26.8 m/s and the final speed of 30 mph to 13.4 m/s. Using the acceleration formula (final velocity minus initial velocity divided by time), the acceleration is found to be [tex]-0.0186 m/s^2[/tex] over the 720 seconds (12 minutes), indicating that the car is decelerating.

To calculate the acceleration of the car, we first need to convert the speeds from miles per hour to meters per second (m/s). Since the car slows down, the acceleration will be negative. The initial speed is 60 mph, which is equivalent to 60  imes 1609/3600 m/s or approximately 26.8 m/s. The final speed is 30 mph, which is equivalent to 30 1609/3600 m/s or approximately 13.4 m/s. The time taken to slow down is 12 minutes, which is 12 60 seconds or 720 seconds. Now we use the formula for acceleration, which is a = (v_f - v_i) / t, where v_f is the final velocity, v_i is the initial velocity, and t is the time taken. Thus, the acceleration a is (13.4 m/s - 26.8 m/s) / 720 s = [tex]-0.0186 m/s^2[/tex]. The negative sign indicates that the car is decelerating.

The velocity of the trainee is 29 m/s or 0.42 rev/s

Acceleration is rate of change of velocity.

[tex]\large {\boxed {a = \frac{v - u}{t} } }[/tex]

[tex]\large {\boxed {d = \frac{v + u}{2}~t } }[/tex]

a = acceleration (m / s²)v = final velocity (m / s)

u = initial velocity (m / s)

t = time taken (s)

d = distance (m)

Centripetal Acceleration of circular motion could be calculated using following formula:

[tex]\large {\boxed {a_s = v^2 / R} }[/tex]

a = centripetal acceleration ( m/s² )

v = velocity ( m/s )

R = radius of circle ( m )

Let us now tackle the problem!

Given:

Radius of horizontal circle = R = 11.0 m

Force Felt by the Trainee = F = 7.80w

Unknown:

Velocity of Rotation = v = ?

Solution:

[tex]F = ma[/tex]

[tex]F = m\frac{v^2}{R}[/tex]

[tex]7.80w = m\frac{v^2}{R}[/tex]

[tex]7.80mg = m\frac{v^2}{R}[/tex]

[tex]7.80g = \frac{v^2}{R}[/tex]

[tex]7.80 \times 9.8 = \frac{v^2}{11.0}[/tex]

[tex]v^2 = 840.84[/tex]

[tex]v \approx 29 ~m/s[/tex]

[tex]\omega = \frac{v}{R}[/tex]  → in rad/s

[tex]\omega = \frac{v}{2 \pi R}[/tex]  → in rev/s

[tex]\omega = \frac{29}{2 \pi \times 11.0}[/tex]

[tex]\omega \approx 0.42 ~ rev/s[/tex]

Grade: High School

Subject: Physics

Chapter: Circular Motion

Keywords: Velocity , Driver , Car , Deceleration , Acceleration , Obstacle , Speed , Time , Rate , Circular , Ball , Centripetal

The speed of trainee in [tex]{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  is [tex]\boxed{29{\text{ }}{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}}[/tex]  and in [tex]{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  is [tex]\boxed{0.42{\text{ }}{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}}[/tex] .

Explanation:

The radius of horizontal circle is [tex]11{\text{ m}}[/tex] .and the force is equal to [tex]7.8[/tex]  times the weight of trainee.

Our aim is to obtain the velocity or speed of trainee in both [tex]{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  and [tex]{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex] .

The weight of the trainee is calculated as,

[tex]W=mg[/tex]

The force is equal to 7.8 times the weight of trainee and is shown below.

[tex]F=7.8mg[/tex]

The expression for centripetal force is shown below.

[tex]{F_{{\text{centripetal}}}}=\frac{{m{v^2}}}{r}[/tex]                                  ......(1)

The radius of circle is [tex]11{\text{ m}}[/tex] .

The centripetal force is equal to the force exerted by trainee.

So, substitute [tex]7.8mg[/tex]  for [tex]{F_{{\text{centripetal}}}}[/tex]  and [tex]11[/tex]  for [tex]r[/tex]  in equation (1) to obtain the value of velocity in [tex]{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex] .

[tex]\begin{aligned}7.8mg&=\frac{{m{v^2}}}{{11}}\\7.8g&=\frac{{{v^2}}}{{11}}\\{v^2}&=85.8g\\\end{aligned}[/tex]

The acceleration due to gravity is [tex]9.8{{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}^{\text{2}}}[/tex] .

Now, the velocity is calculated as,

[tex]\begin{gathered}{v^2}=85.8\left({9.8}\right)\\=840.84\\v=\sqrt{840.84}\\=28.99\\\approx29{\text{ }}{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}\\\end{gathered}[/tex]

Therefore, the velocity of trainee in [tex]{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  is approximately [tex]29{\text{ }}{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex] .

The expression for angular velocity in [tex]{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  is shown below.

[tex]\begin{aligned}\omega&=\frac{v}{2\pi r}\end{aligned}[/tex]         ... (2)

The obtained velocity is [tex]29{\text{ }}{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex] , so substitute [tex]29[/tex]  for [tex]v[/tex]  and [tex]11[/tex]  for [tex]r[/tex]  in equation (2) to obtain the angular velocity.

[tex]\begin{aligned}\omega&=\frac{29}{2\pi(11)}\\&=0.419\\&\approx0.42\text{ rev/s}\end{aligned}[/tex]

Therefore, the angular velocity in [tex]{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  is [tex]0.42{\text{ }}{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace} {\text{s}}}[/tex] .

Thus, the speed of trainee in [tex]{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  is [tex]\boxed{29{\text{ }}{{\text{m}}\mathord{\left/{\vphantom{{\text{m}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}}[/tex]  and in [tex]{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}[/tex]  is [tex]\boxed{0.42{\text{ }}{{{\text{rev}}}\mathord{\left/{\vphantom{{{\text{rev}}}{\text{s}}}}\right.\kern-\nulldelimiterspace}{\text{s}}}}[/tex] .

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Answer Details:

Grade: High School

Subject: Physics

Chapter: Circular Motion

Keywords:

Device, astronauts, jet, pilots, rotation, trainee, horizontal, force, weight, fast, m/s, rev/s, tangential, velocity, speed, angular, centripetal.

The force on the body of mass 25 kg is 300 N then the acceleration of the body will be equal to 12 m/s².

The rate of change in an object's velocity with respect to time is known as acceleration in mechanics. The vector quantity of accelerations. The direction of the net force that is acting on an object determines its acceleration.

Since acceleration has both a magnitude and a direction, it is a vector quantity. Velocity is a vector quantity as well. The definition of acceleration is the change in velocity vector over a time interval divided by the time interval.

As per the information given in the question,

Force, F = 300 N

Mass, m = 25 kg

Use the formula of force,

F = ma

300 N = 25 × a

a = 300/25

a = 12 m/s²

Therefore, the acceleration is 12 m/s².

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Window glass is a better conductor of thermal energy than a plastic foam cup which acts as a good thermal insulator, slowing down the transfer of heat. The foam cup is better at keeping the heat in, while the window glass allows more heat to pass through.

In the comparison between window glass and a plastic foam cup, the better conductor of thermal energy is window glass. Some materials conduct thermal energy faster than others. Materials like glass and metals are generally good heat conductors, whereas materials such as plastic and rubber are poor heat conductors. Plastic foam like polystyrene foam seen in disposable cups is actually a good thermal insulator, meaning it slows down the transfer of heat. As such, it's great for keeping your coffee hot by reducing heat transfer from the coffee to the environment.

On the other hand, window glass, while not as conductive as metals, still conducts heat at a much faster rate than plastic foam. It is therefore less effective as a thermal insulator, which is why you may feel the cold through a window on a chilly day. Window glass is seen as a major region of heat transfer in buildings, as it allows heat to escape from the interior to the exterior.

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Final answer

The wavelength of the light, to the nearest whole number, is 684 nm.

The formula for the diffraction grating is given by d sin( heta) = m extlambda, where d is the distance between adjacent gratings,  heta is the angle of diffraction, m represents the order of the maximum, and  extlambda is the wavelength of the light. For a grating with 200.0 lines per mm, the distance d is the inverse of the number of lines per meter, which is 1/(200,000) meters or 5 x 10^-6 m. The given second-order dark band (m=2) forms at a 20.0°(diffraction angle). Using these values in the diffraction grating equation, solving for  extlambda yields a wavelength of approximately 684 nm. This can be calculated as follows: 5 x 10^-6 m * sin(20.0°) = 2 extlambda, leading to  extlambda approximately equals 684 nm after computation.

Answer:

satphone

Explanation:

plato users

Answer:

Explanation:

sat phone

common knowledge mate

The gas is chlorine gas

Density at STP = 3.16 g per L

1 mole of a gas at STP occupies, 22.4 L

Therefore, it means mass of the gas in 22.4 L that is 1 mol gas will be;

= 3.16 g × 22.4 L

= 70.8 g/mol

≈ 71 g/mol

The identity of the gas would be Chlorine gas, whose molar mass is 71 g/mol

Given the density of the gas at standard temperature and pressure, we can use the molar volume of a gas at STP to determine the molar mass. Using this process, the gas is likely to be Bromine (Br2).

The density given is a key factor to determine the gas. Because the question refers to standard temperature and pressure (stp), we can use the known molar volume of a gas at stp, which is 22.4 L/mol. Based on the given density and the molar volume, we can calculate the molar mass of the unknown gas:

Density = Molar mass / molar volume,

so Molar mass = Density x molar volume = 3.16 g/L x 22.4 L/mol = 70.784 g/mol.

Based on common molar masses, this results indicates that the unknown gas is most likely Bromine (Br2), as its molar mass is approximately 79.9 g/mol, the closest common molar mass to 70.784 g/mol.

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Answer:B

Explanation: Because the weight will be greater with one leg lifted up in the air, it will make the weight more.

Lesson 9: Fluid Pressure (connexus students!)

1.D) 3 n/m^2

2.C) 2 meters below the surface of a swimming pool

3.B) cork

4.A) depends only on the type of fluid

5.A) the air pressure decreases

Dorsiflexion, as the word suggests, is the action of bending the foot upward at the ankle. In activities like walking, running, or ascending stairs, it is a typical movement. Plantar flexion is the term for the opposite motion.

Dorsiflexion is the name given to the process of bending the foot upward at the ankle. This is a typical movement when doing a variety of activities where your foot's position changes in relation to your leg, like walking, running, or ascending stairs. Plantar flexion is the term for the motion that pushes your foot downward in the opposite direction.

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Dorsiflexion refers to bending the foot upward at the ankle. This is one of the two primary movements at the ankle joint, the other being plantar flexion which involves lifting the heel or pointing the toes downward.

The term that refers to bending the foot upward at the ankle is called dorsiflexion. This movement is characterized by lifting the front of the foot so that the top of the foot moves toward the anterior leg. Dorsiflexion is one of two primary movements at the ankle joint. The opposite movement to dorsiflexion is plantar flexion, which involves lifting the heel of the foot from the ground or pointing the toes downward. These two movements, dorsiflexion and plantar flexion, are the only movements available at the ankle joint.

Dorsiflexion is the term that means to bend the foot upward at the ankle. It is a movement at the ankle joint where the top of the foot moves towards the anterior leg. This movement is opposite to plantar flexion, which is the bending of the foot downward at the ankle.

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