Question 1

According to Noether’s theorem, which conservation law is associated with rotational symmetry?

Accepted Answer

Conservation of angular momentum

Question 2

A 2 kg object is dropped from a height of 5 m. Ignoring air resistance, what is its kinetic energy just before hitting the ground? (Use $$g = 9.8 \ \mathrm{m/s^2$})$$

Accepted Answer

$$98 \ \mathrm{J}$$

Question 3

Which of the following best describes the work done by friction on a box sliding across a rough surface?

Accepted Answer

Friction does negative work, decreasing the box's kinetic energy.

Question 4

A force $$\vec{F}$$ acts at an angle $$	heta to $$the displacement $$\Delta \vec{r}. $$Which formula gives the work done by this force?

Accepted Answer

$$W = F \Delta r \cos 	heta$$

Question 5

A child on a swing is momentarily at rest at the highest point. As the swing moves downward, which energy transformation occurs?

Accepted Answer

Gravitational potential energy to kinetic energy

Question 6

A skier glides down a slope at constant speed. What energy transformation is primarily taking place?

Accepted Answer

Potential energy to thermal energy

Question 7

Which of the following is the correct SI unit for energy?

Accepted Answer

$$\mathrm{kg \cdot m^2$ \cdot s$$^{-2}$$}$$

Question 8

A force $$F(x)$$ varies with position $$x. $$The total work done by this force as an object moves from $$x_i to$$ $$x_f is $$given by:

Accepted Answer

$$W = \int_{x_i}^{x_f} F(x) dx$$

Question 9

A ball A has half the mass and eight times the kinetic energy of ball B. What is the ratio of their speeds $$v_A/v_B$$?

Accepted Answer

$$4$$

Question 10

Which of the following is an example of energy transformation from chemical energy to kinetic energy?

Accepted Answer

A person running after eating food

Question 11

A box is pushed 3 m by a constant force of 10 N at an angle of $$0^\circ to $$the direction of motion. How much work is done?

Accepted Answer

$$30 \ \mathrm{J}$$

Question 12

Which force does the most work if all three forces act over the same displacement: $$10 \ \mathrm{N} at$$ $$90^\circ$$, $$8 \ \mathrm{N} at$$ $$60^\circ$$, $$6 \ \mathrm{N} at$$ $$0^\circ to $$the displacement?

Accepted Answer

The 6 N force

Question 13

A 1 kg object is dropped from a height of 1 m. What is its speed just before hitting the ground? (Use $$g = 9.8 \ \mathrm{m/s^2$})$$

Accepted Answer

$$4.4 \ \mathrm{m/s}$$

Question 14

Which of the following is NOT a form of energy discussed in the materials?

Accepted Answer

Magnetic monopole energy

Question 15

A person pushes against a wall for 10 minutes but the wall does not move. How much work is done by the person?

Accepted Answer

Zero work

Question 16

Which of the following best describes the law of conservation of energy?

Accepted Answer

Energy can change forms but the total energy remains constant in a closed system.

Question 17

The area under a force vs. displacement graph represents:

Accepted Answer

The work done by the force

Question 18

Which of the following is the correct expression for kinetic energy?

Accepted Answer

$$K = \frac{1}{2}mv^2$

Question 19

A slingshot is pulled back, storing energy. What type of energy is primarily stored in the stretched slingshot?

Accepted Answer

Elastic potential energy

Conservation of Energy and Work: Physics Study Guide

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