Unit 3 Work and Power Summative Review (no simple machines)

A roller coaster's motion results from the application of force and energy. Which of the following are accurate:

• Motion cannot occur without the constant application of force

• Energy is conserved; it cannot be created or detroyed

• Motion is the result of applying force over a distance

• the terms energy and force describe similar but different ideas

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

NGSS.HS-PS3-1

it takes 20,000 N to move a roller coaster to the top of a 200 m track. What is the work needed to perform this task?

• 100 J

• 4,000,000 J

• 20,000 J

• 2,000,000 J

It takes 20,000 N to move a roller coaster to the top of a 200 m track. If it takes 40 seconds to reach the top, what is the power used to perform this task?

• 4,000,000 W

• 100,000 W

• 500 W

• 160,000,000 W

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NGSS.HS-PS2-1

If we calculate that it takes 20,000 N of force to move a coaster up a hill, and measurement shows it takes a force of 30,000 N. What must be true based on this?

• More force and work are needed to overcome the negative work done by friction

• Less power will be needed to raise the coaster in the same amount of time

• More power will be needed to raise the coaster in the same amount of time

• The potential energy will be higher, than it would be if it took 20,000 N

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NGSS.HS-PS2-1

As a roller coaster is being pulled up the first hill. Which of the following claims are true:

• As the coaster moves higher, it gains potential energy.

• Work is being performed by the motor to increase the total energy of the system.

• If the coaster stops at the top of the hill, the potential energy is maximized and the kinetic energy is zero.

• At the very bottom of the hill, potential energy and kinetic energy are maximized.

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NGSS.HS-PS3-1

NGSS.HS-PS3-2

If the second hill of the roller coaster is the same height as the first, and the roller coaster has zero velocity at the top of the first hill before rolling done. Would the coaster make it to the top of the second hill

• Yes, they have the same potential energy

• No, the potential energy of the second hill is more than the first

• No, some of the energy will be lost to friction.

• Yes, all of the kinetic energy at the bottom will be conserved.

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NGSS.HS-PS2-1

The mass of the roller coaster is 4500 kg and the first hill is 100 M tall. What would the maximum speed of the coaster be?

• 90,000 m/s

• 300 m/s

• 30 m/s

• 44.7 m/s

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NGSS.HS-PS3-1

NGSS.HS-PS3-2

Select all of the conservative forces

• Friction

• Gravity

• Elastic

• Air resistance

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NGSS.HS-PS2-4

What are non-conservative forces? (Select all that apply)

• Air Resistance

• Friction

• Gravity

• Elastic

• Forces that lose energy to a non-useable form

Using different size gears changes the amount of force needed to do work, but changing the distance over which the work is done. Therefore, larger gears require ____________ force for the same amount of work.

• More

• Less

• Same amount of

• Unknown

Answer explanation

Larger gears increase the distance over which work is done. W = Fd, so if distance goes up, Force needed to do the work goes down.

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NGSS.HS-PS2-1