Question 1

Which of the following statements best describes the concept of energy in physics?

Accepted Answer

Energy is the ability to do work.

Question 2

A person holds a heavy weight overhead without moving it. Why is the work done by the person on the weight zero?

Accepted Answer

Because the displacement of the weight is zero.

Question 3

Which equation correctly expresses the relationship between mass and energy according to Einstein's mass-energy equivalence?

Accepted Answer

$$E = mc^2$

Question 4

A 5 kg box is pushed with a net force of 10 N over a frictionless surface for 4 meters, starting from rest. What is the final speed of the box?

Accepted Answer

$$v = 4 	ext{ m/s}$$

Question 5

Which of the following is NOT a form of potential energy?

Accepted Answer

Kinetic

Question 6

A constant force $$F_0$$ acts on an object that moves a distance $$\Delta x. In $$case 1, the force is parallel to the displacement. In case 2, the force is at an angle $$	heta to $$the displacement. Which case results in greater work done by the force?

Accepted Answer

Case 1

Question 7

The work done by a force $$\vec{F}$$ over a displacement $$\vec{\Delta x} is $$given by which mathematical operation?

Accepted Answer

$$W = \vec{F} \cdot \vec{\Delta x}$$

Question 8

A car is moving at a constant speed on a flat road. A force is applied in the direction of motion and the car's speed increases. What can you say about the net work done on the car?

Accepted Answer

The net work is positive.

Question 9

Which of the following is true about kinetic energy?

Accepted Answer

It is given by $$KE = \frac{1}{2}mv^2$ and is always positive for real mass and velocity.

Question 10

A 5.0-kg parcel slides down a 2.0-m tall ramp starting from rest and reaches a final kinetic energy of 56 J. How much work did nonconservative forces do?

Accepted Answer

$$-42 	ext{ J}$$

Question 11

Which statement is most likely to be correct about the total mechanical energy of a parcel that slides down a rough ramp?

Accepted Answer

Total mechanical energy decreases with time.

Question 12

Which of the following forces is always nonconservative?

Accepted Answer

Frictional force

Question 13

A boy is riding on a Ferris wheel. The wheel makes one complete turn. The work done by the force of Earth's gravity on the boy is:

Accepted Answer

Zero

Question 14

Which formula gives the gravitational potential energy (GPE) of an object of mass $$m at $$height $$h$$ above the ground?

Accepted Answer

$$GPE = mgh$$

Question 15

Three objects of equal mass start at the same height and move down the same vertical distance $$H. $$One falls straight down, one slides down a frictionless incline, and one swings on a string. In which case is the net work done by all forces during the motion the greatest?

Accepted Answer

All the same

Question 16

A cart lies on a frictionless air track. You apply a constant force $$F to $$the cart until it has moved a distance $$d$$ from its starting position. At this point the cart has a speed of $$10 	ext{ m/s}. If $$you were to apply a force $$2F$$ over the same distance, what would be the final speed of the cart?

Accepted Answer

$$14.14 	ext{ m/s}$$

Question 17

Which of the following statements about conservative forces is correct?

Accepted Answer

Work done by a conservative force is independent of the path taken.

Question 18

If only conservative forces act on a system, what is true about the total mechanical energy?

Accepted Answer

It remains constant.

Question 19

Which equation represents the work-energy theorem for a system with both conservative and nonconservative forces?

Accepted Answer

$$W_{net} = \Delta K = W_c + W_{nc}$$

Question 20

A 5-kg parcel slides down a 2-m tall ramp starting from rest. Friction and air resistance are negligible. How fast will the parcel be at the end of the ramp?

Accepted Answer

$$v = 6 	ext{ m/s}$$

Work, Kinetic Energy, and Conservation of Energy: Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드