Question 1

Which of the following best describes the work-energy theorem?

Accepted Answer

The net work done on an object is equal to the change in its kinetic energy: $$W_{net} = K_f - K_i$$

Question 2

A box of mass $$m is $$pushed up a frictionless ramp of height $$h. $$What is the minimum work required to move the box to the top?

Accepted Answer

$$W = mgh$$

Question 3

Which of the following is a non-conservative force?

Accepted Answer

Friction

Question 4

A wind turbine converts which forms of energy into electrical energy?

Accepted Answer

Kinetic energy of wind to electrical energy

Question 5

A spring with spring constant $$k is $$compressed by a distance $$x. $$What is the potential energy stored in the spring?

Accepted Answer

$$U = \frac{1}{2}kx^2$

Question 6

If only conservative forces act on a system, what happens to the total mechanical energy?

Accepted Answer

It remains constant throughout the motion.

Question 7

A 60.0-kg woman runs up a 3.0-m high flight of stairs in 4.0 s, starting from rest and reaching a final speed of 2.0 m/s. What is her average power output?

Accepted Answer

$$P = \frac{mgh + \frac{1}{2}mv^2$}{t}$$

Question 8

Which statement about kinetic energy is correct?

Accepted Answer

Kinetic energy is a scalar quantity and is always non-negative.

Question 9

A block of mass $$m is $$released from rest at height $$h$$ and slides down a frictionless ramp. What is its speed at the bottom?

Accepted Answer

$$v = \sqrt{2gh}$$

Question 10

Which of the following scenarios involves negative work being done?

Accepted Answer

A person applies a force opposite to the direction of motion, slowing down a moving cart.

Question 11

A leaf falls to the ground at constant speed due to air resistance. How does its final mechanical energy compare to its initial mechanical energy?

Accepted Answer

Final mechanical energy is less than initial mechanical energy.

Question 12

The work done by gravity on a car driving to school is:

Accepted Answer

The same regardless of the path taken, as long as the starting and ending heights are the same.

Question 13

A spring is stretched from $$x_1 to$$ $$x_2. $$What is the work done by the spring?

Accepted Answer

$$W = -\frac{1}{2}k(x_2$^2 - x_1$^2)$$

Question 14

A block of mass $$m is $$shot up a frictionless ramp by a spring compressed by $$x. $$What is the maximum height $$h$$ the block reaches?

Accepted Answer

$$h = \frac{kx^2$}{2mg}$$

Question 15

Which of the following is true about conservative forces?

Accepted Answer

The work done by a conservative force depends only on the initial and final positions.

Question 16

A cart of mass $$m is $$acted on by a net force $$F$$ over a displacement $$d. $$What is the work done by the net force?

Accepted Answer

$$W = Fd$$

Question 17

If a force $$F is $$applied at an angle $$	heta to $$the direction of displacement $$d$$, what is the work done?

Accepted Answer

$$W = Fd \cos 	heta$$

Question 18

Which of the following is the correct expression for gravitational potential energy?

Accepted Answer

$$U = mgy$$

Question 19

A motor must lift an elevator of mass $$M$$ and passengers of mass $$m at $$constant speed $$v. $$What power must the motor deliver?

Accepted Answer

$$P = (M + m)gv$$

Question 20

Which of the following is true about the area under a force vs. position graph?

Accepted Answer

It represents the work done by the force over the displacement.

Work, Energy, and Conservation: Physics Study Notes

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