Q: Which of the following best describes the work done by a force $$\vec{F}$$ acting at an angle $$\theta to $$the direction of displacement $$\vec{d}$$?

$$W = F \cdot d \cdot \cos \theta$$

Q: Which of the following best describes the kinetic energy of a rotating object?

$$K_{\text{rot}} = \frac{1}{2} I \$$omega^2$$

Question 1

Which of the following best describes the work done by a force $$\vec{F}$$ acting at an angle $$	heta to $$the direction of displacement $$\vec{d}$$?

Accepted Answer

$$W = F \cdot d \cdot \cos 	heta$$

Question 2

A 2.0 kg book is lifted vertically by 1.5 m at constant speed. What is the work done by gravity during this process? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$-29.4\ \mathrm{J}$$

Question 3

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

Accepted Answer

Magnetic energy

Question 4

A shopper pushes a cart with a force of $$35.0\ \mathrm{N} at an $$angle of $$25.0^\circ$$ below the horizontal for $$50.0\ \mathrm{m}. $$What is the work done by the shopper's force? (Use $$\cos 25.0^\circ = 0.906)$$

Accepted Answer

$$1,587\ \mathrm{J}$$

Question 5

Which equation correctly expresses the work-kinetic energy theorem?

Accepted Answer

$$W_{	ext{net}} = k_f - k_i$$

Question 6

A car of mass $$1167\ \mathrm{kg}$$ accelerates from $$10.0\ \mathrm{m/s} to a $$final speed after $$4.00 	imes 10^5$\ \mathrm{J} of $$work is done. What is the final speed of the car?

Accepted Answer

$$27.6\ \mathrm{m/s}$$

Question 7

A $$60.0\ \mathrm{kg}$$ object slides on a horizontal surface with an initial speed of $$25.0\ \mathrm{m/s}. If $$the kinetic friction force is $$50.0\ \mathrm{N}$$, how far will it slide before coming to a stop?

Accepted Answer

$$375\ \mathrm{m}$$

Question 8

Which of the following best describes the kinetic energy of a rotating object?

Accepted Answer

$$K_{	ext{rot}} = \frac{1}{2} I \$$omega^2$$

Question 9

A solid uniform ball of mass $$0.125\ \mathrm{kg}$$ rolls without slipping at $$4.5\ \mathrm{m/s}. $$What is its rotational kinetic energy just before it hits the floor? (Moment of inertia for a solid sphere: $$I = \frac{2}{5}mr^2$)

Accepted Answer

$$0.227\ \mathrm{J}$$

Question 10

Which of the following statements about work is correct?

Accepted Answer

Work can be positive, negative, or zero depending on the direction of force relative to displacement.

Question 11

A spring is stretched by $$0.20\ \mathrm{m}$$ from its equilibrium position. If the spring constant is $$150\ \mathrm{N/m}$$, what is the elastic potential energy stored in the spring?

Accepted Answer

$$3.0\ \mathrm{J}$$

Question 12

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

Accepted Answer

$$U_g = mgh$$

Question 13

A $$5.0\ \mathrm{kg}$$ object is dropped from a height of $$10.0\ \mathrm{m}. $$What is its kinetic energy just before it hits the ground? (Neglect air resistance, $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$490\ \mathrm{J}$$

Question 14

Which of the following best describes thermal energy?

Accepted Answer

The sum of the kinetic and potential energies of all the molecules in an object.

Question 15

A $$3.0\ \mathrm{kg}$$ object is moving at $$6.0\ \mathrm{m/s}. $$What is its kinetic energy?

Accepted Answer

$$54\ \mathrm{J}$$

Question 16

Which of the following scenarios involves negative work being done?

Accepted Answer

A person lowers a box at constant speed.

Question 17

A rolling ball has which types of kinetic energy?

Accepted Answer

Both translational and rotational kinetic energy.

Question 18

Which of the following is a correct implication of the work-kinetic energy theorem?

Accepted Answer

If net work is done on an object, its kinetic energy will change.

Ch.10 Energy and Work: Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드