Work-Energy Review CP1

1

Which of the following statements are true about work? Include all that apply.

Work is a form of energy.

A Watt is the standard metric unit of work.

Units of work would be equivalent to a Newton times a meter.

A kg\cdot m^2/s^2 would be a unit of work.

Work is a time-based quantity; it is dependent upon how fast a force displaces an object.

Superman applies a force on a truck to prevent it from moving down a hill. This is an example of work being done.

An upward force is applied to a bucket as it is carried 20 m across the yard. This is an example of work being done.

A force is applied by a chain to a roller coaster car to carry it up the hill of the first drop of the Shockwave ride. This is an example of work being done.

The force of friction acts upon a softball player as she makes a headfirst dive into third base. This is an example of work being done.

An eraser is tied to a string; a person holds the string and applies a tension force as the eraser is moved in a circle at constant speed. This is an example of work being done.

A force acts upon an object to push the object along a surface at constant speed. By itself, this force must NOT be doing any work upon the object.

A force acts upon an object at a 90-degree angle to the direction that it is moving. This force is doing negative work upon the object.

An individual force does NOT do positive work upon an object if the object is moving at constant speed.

An object is moving to the right. A force acts leftward upon it. This force is doing negative work.

A non-conservative force is doing work on an object; it is the only force doing work. Therefore, the object will either gain or lose mechanical energy.

1

Which of the following statements are true about power? Include all that apply.

Power is a time-based quantity.

Power refers to how fast work is done upon an object.

Powerful people or powerful machines are simply people or machines which always do a lot of work.

A force is exerted on an object to move it at a constant speed. The power delivered by this force is the magnitude of the force multiplied by the speed of the object.

The standard metric unit of power is the Watt.

If person A and person B do the same job but person B does it faster, then person A does more work but person B has more power.

The Newton•meter is a unit of power.

A 60-kg boy runs up a 2.0 meter staircase in 1.5 seconds. His power is approximately 80 Watt.

A 300-Newton force is applied to a skier to drag her up a ski hill at a constant speed of 1.5 m/s. The power delivered by the toe rope is 450 Watts.

1

Which of the following statements are true about kinetic energy? Include all that apply.

1

Which of the following statements are true about potential energy? Include all that apply.

For the next batch of multiple choice questions, use g = 10 \,m/s^2

1

A 1200 kg car and a 2400 kg car are lifted to the same height at a constant speed in a auto service station. Lifting the more massive car requires ____ work.

1

An arrow is drawn back so that 50 Joules of potential energy is stored in the stretched bow and string. When released, the arrow will have a kinetic energy of ____ Joules.

50

more than 50

less than 50

1

A child lifts a box up from the floor. The child then carries the box with constant speed to the other side of the room and puts the box down. How much work does he do on the box while walking across the floor at constant speed?

zero joules

more than zero joules

more information needed to determine

1

A 1000-kg car is moving at 40.0 km/hr when the driver slams on the brakes and skids to a stop (with locked brakes) over a distance of 20.0 meters. How far will the car skid with locked brakes if it is traveling at 120. km/hr?

1

A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water.

1

A ball is projected into the air with 100 J of kinetic energy. The kinetic energy is transformed into gravitational potential energy on the path towards the peak of its trajectory. When the ball returns to its original height, its kinetic energy is ____ Joules. Do consider the effects of air resistance.

less than 100

100

more than 100

not enough information given

1

During a construction project, a 2500 N object is lifted high above the ground. It is released and falls 10.0 meters and drives a post 0.100 m into the ground. The average impact force on the object is ____ Newtons.

2,500

25,000

250,000

2,500,000

1

A 10-Newton object moves to the left at 1 m/s. Its kinetic energy is approximately ____ Joules.

0.5

1.0

10

more than 10

1

Luke Autbeloe stands on the edge of a roof and throws a ball downward. It strikes the ground with 100 J of kinetic energy. Luke now throws another identical ball upward with the same initial speed, and this too falls to the ground. Neglecting air resistance, the second ball hits the ground with a kinetic energy of ____ J.

1

An object at rest may have __________.

1

A 50-kg platform diver hits the water below with a kinetic energy of 5000 Joules. The height (relative to the water) from which the diver dove was approximately ____ meters.

5

10

50

100

1

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of , but different amounts of . Pick the two words which fill in the blanks in their respective order.

1

Which requires more work: lifting a 50.0 kg crate a vertical distance of 2.0 meters or lifting a 25.0 kg crate a vertical distance of 4.0 meters?

lifting the 50 kg crate

lifting the 25 kg crate

both require the same amount of work

1

A 50.0 kg crate is lifted to a height of 2.0 meters in the same time as a 25.0 kg crate is lifted to a height of 4 meters. The rate at which energy is used (i.e., power) in raising the 50.0 kg crate is ____ as the rate at which energy is used to lift the 25.0 kg crate.

twice as much

half as much

the same

1

Using 1000. J of work, a small object is lifted from the ground floor to the third floor of a tall building in 20.0 seconds. What power was required in this task?

An 878-kg car skids to a stop across a horizontal surface over a distance of 45.2 m. The average force acting upon the car is 7160 N. Determine ...

null

1

the work done upon the car.

1

the initial kinetic energy of the car.

1

the acceleration of the car.

1

the initial velocity of the car.

A 51.7-kg hiker ascends a 43.2-meter high hill at a constant speed of 1.20 m/s. If it takes 384 s to climb the hill, then determine ...

null

1

kinetic energy change of the hiker.

1

the potential energy change of the hiker.

1

the work done upon the hiker.

1

Work-Energy Review CP1

Which of the following statements are true about work? Include all that apply.

Which of the following statements are true about power? Include all that apply.

Which of the following statements are true about kinetic energy? Include all that apply.

Which of the following statements are true about potential energy? Include all that apply.

A 1200 kg car and a 2400 kg car are lifted to the same height at a constant speed in a auto service station. Lifting the more massive car requires ____ work.

An arrow is drawn back so that 50 Joules of potential energy is stored in the stretched bow and string. When released, the arrow will have a kinetic energy of ____ Joules.

A child lifts a box up from the floor. The child then carries the box with constant speed to the other side of the room and puts the box down. How much work does he do on the box while walking across the floor at constant speed?

A 1000-kg car is moving at 40.0 km/hr when the driver slams on the brakes and skids to a stop (with locked brakes) over a distance of 20.0 meters. How far will the car skid with locked brakes if it is traveling at 120. km/hr?

A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water.

During a construction project, a 2500 N object is lifted high above the ground. It is released and falls 10.0 meters and drives a post 0.100 m into the ground. The average impact force on the object is ____ Newtons.

A 10-Newton object moves to the left at 1 m/s. Its kinetic energy is approximately ____ Joules.

An object at rest may have __________.

A 50-kg platform diver hits the water below with a kinetic energy of 5000 Joules. The height (relative to the water) from which the diver dove was approximately ____ meters.

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of ____, but different amounts of ____. Pick the two words which fill in the blanks in their respective order.

Which requires more work: lifting a 50.0 kg crate a vertical distance of 2.0 meters or lifting a 25.0 kg crate a vertical distance of 4.0 meters?

A 50.0 kg crate is lifted to a height of 2.0 meters in the same time as a 25.0 kg crate is lifted to a height of 4 meters. The rate at which energy is used (i.e., power) in raising the 50.0 kg crate is ____ as the rate at which energy is used to lift the 25.0 kg crate.

Using 1000. J of work, a small object is lifted from the ground floor to the third floor of a tall building in 20.0 seconds. What power was required in this task?

the work done upon the car.

the initial kinetic energy of the car.

the acceleration of the car.

the initial velocity of the car.

kinetic energy change of the hiker.

the potential energy change of the hiker.

the work done upon the hiker.

the power delivered by the hiker.

Which of the following statements are true about work? Include all that apply.

Which of the following statements are true about power? Include all that apply.

Which of the following statements are true about kinetic energy? Include all that apply.

Which of the following statements are true about potential energy? Include all that apply.

A 1200 kg car and a 2400 kg car are lifted to the same height at a constant speed in a auto service station. Lifting the more massive car requires ____ work.

An arrow is drawn back so that 50 Joules of potential energy is stored in the stretched bow and string. When released, the arrow will have a kinetic energy of ____ Joules.

A child lifts a box up from the floor. The child then carries the box with constant speed to the other side of the room and puts the box down. How much work does he do on the box while walking across the floor at constant speed?

A 1000-kg car is moving at 40.0 km/hr when the driver slams on the brakes and skids to a stop (with locked brakes) over a distance of 20.0 meters. How far will the car skid with locked brakes if it is traveling at 120. km/hr?

A platform diver weighs 500 N. She steps off a diving board that is elevated to a height of 10 meters above the water. The diver will possess ___ Joules of kinetic energy when she hits the water.

During a construction project, a 2500 N object is lifted high above the ground. It is released and falls 10.0 meters and drives a post 0.100 m into the ground. The average impact force on the object is ____ Newtons.

A 10-Newton object moves to the left at 1 m/s. Its kinetic energy is approximately ____ Joules.

An object at rest may have __________.

A 50-kg platform diver hits the water below with a kinetic energy of 5000 Joules. The height (relative to the water) from which the diver dove was approximately ____ meters.

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of ____, but different amounts of ____. Pick the two words which fill in the blanks in their respective order.

Which requires more work: lifting a 50.0 kg crate a vertical distance of 2.0 meters or lifting a 25.0 kg crate a vertical distance of 4.0 meters?

A 50.0 kg crate is lifted to a height of 2.0 meters in the same time as a 25.0 kg crate is lifted to a height of 4 meters. The rate at which energy is used (i.e., power) in raising the 50.0 kg crate is ____ as the rate at which energy is used to lift the 25.0 kg crate.

Using 1000. J of work, a small object is lifted from the ground floor to the third floor of a tall building in 20.0 seconds. What power was required in this task?

the work done upon the car.

the initial kinetic energy of the car.

the acceleration of the car.

the initial velocity of the car.

kinetic energy change of the hiker.

the potential energy change of the hiker.

the work done upon the hiker.

the power delivered by the hiker.

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of , but different amounts of . Pick the two words which fill in the blanks in their respective order.

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount of , but different amounts of . Pick the two words which fill in the blanks in their respective order.