Question 1

Which of the following best describes the work done by a variable force $$F(x) as an $$object moves from $$x_i to$$ $$x_f$$?

Accepted Answer

The area under the $$F vs$$. $$x$$ curve between $$x_i$$ and $$x_f.$$

Question 2

A block of mass $$m$$ slides across a rough horizontal surface and comes to rest after traveling a distance $$d. If $$the coefficient of kinetic friction is $$\mu_k$$, what is the total thermal energy generated due to friction?

Accepted Answer

$$\mu_k m g d$$

Question 3

Two objects, one of mass $$m$$ and the other of mass $$2m$$, are dropped from the same height. Neglecting air resistance, which statement is true when they hit the ground?

Accepted Answer

Both objects have the same velocity.

Question 4

Three identical balls are thrown from the top of a building with the same initial speed but in different directions. Neglecting air resistance, how do their speeds compare when they hit the ground?

Accepted Answer

All three balls have the same speed.

Question 5

A child slides down two different frictionless slides of the same height but different shapes. Which of the following is true about their speeds at the bottom?

Accepted Answer

Both children have the same speed at the bottom.

Question 6

Which of the following is the correct expression for gravitational potential energy near Earth's surface?

Accepted Answer

$$U = mgh$$

Question 7

A 15 kg penguin slides on ice with an initial speed of 5 m/s and comes to rest after 12.8 m. If $$\mu_k = 0.1$$, what was the main energy transformation?

Accepted Answer

Kinetic energy was converted to thermal energy due to friction.

Question 8

If a block slides on a frictionless surface, which of the following statements is true about the system's energy?

Accepted Answer

The total mechanical energy is conserved.

Question 9

A block slides on a rough surface and comes to rest. If the system is defined as the block only, is the system isolated?

Accepted Answer

No, because energy leaves the block due to friction.

Question 10

A block slides on a rough surface and comes to rest. If the system is defined as the block plus the surface, is the system isolated?

Accepted Answer

Yes, because energy is transformed within the system.

Question 11

Which equation correctly relates the work done by a constant force $$F$$ over a distance $$d at an $$angle $$	heta to $$the direction of motion?

Accepted Answer

$$W = F d \cos 	heta$$

Question 12

A block of mass $$m is $$pushed across a horizontal surface with friction. The friction force is $$f_k = \mu_k m g. $$What is the work done by friction after the block moves a distance $$d$$?

Accepted Answer

$$-\mu_k m g d$$

Question 13

A 15 kg penguin slides to a stop from 5 m/s on ice with $$\mu_k = 0.1. $$What is the stopping distance?

Accepted Answer

$$12.8 m$$

Question 14

A block slides down a frictionless ramp of height $$h. $$What is its speed at the bottom?

Accepted Answer

$$\sqrt{2gh}$$

Question 15

A block slides down a rough ramp and comes to rest after traveling a distance $$d. If$$ $$\mu_k is $$the coefficient of kinetic friction, what is the relationship between $$h$$ and $$d$$?

Accepted Answer

$$h = \mu_k d$$

Question 16

Which of the following is true about the energy lost to friction in a sliding block scenario?

Accepted Answer

It is always positive and increases the system's thermal energy.

Question 17

If a block is pushed with a force $$F$$ that varies with position $$x$$, what is the mathematical expression for the work done?

Accepted Answer

$$W = \int F(x) dx$$

Question 18

A block of mass $$m is $$dropped from height $$h$$ and lands with speed $$v. $$Which equation relates $$v to$$ $$h$$?

Accepted Answer

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

Question 19

Which of the following is a correct statement about isolated systems?

Accepted Answer

The total energy of an isolated system remains constant.

Conservation of Energy: Work, Kinetic Energy, Potential Energy, and Friction

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