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: 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?

$$W_{gravity} = 2.0 \times 9.8 \times 1.5 \times \cos 180^\circ$$

Q: 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?

$$W = 35.0 \times 50.0 \times \cos 25.0^\circ$$

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?

Accepted Answer

$$W_{gravity} = 2.0 	imes 9.8 	imes 1.5 	imes \cos 180^\circ$$

Question 3

Which form of energy is stored in the bonds between molecules?

Accepted Answer

Chemical energy

Question 4

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

Accepted Answer

$$v_f = \sqrt{v_i^2$ + \frac{2W}{m}}$$

Question 5

Which equation correctly expresses the work-kinetic energy theorem?

Accepted Answer

$$k_i + W_{net} = k_f$$

Question 6

A 60.0 kg object slides on a horizontal surface with an initial speed of 25.0 m/s. The kinetic friction force is 50.0 N. How far does the object slide before coming to a stop?

Accepted Answer

$$d = \frac{m v_i^2$}{2 F_{friction}}$$

Question 7

Which of the following is the correct expression for the translational kinetic energy of an object of mass $$m$$ moving at speed $$v$$?

Accepted Answer

$$K = \frac{1}{2} m v^2$

Question 8

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?

Accepted Answer

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

Question 9

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

Accepted Answer

Magnetic energy

Question 10

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?

Accepted Answer

$$W = 35.0 	imes 50.0 	imes \cos 25.0^\circ$$

Question 11

Which of the following statements about the work done by gravity when lifting an object upward is correct?

Accepted Answer

Gravity does negative work when lifting an object upward.

Question 12

Which formula gives the rotational kinetic energy of a rotating object with moment of inertia $$I$$ and angular speed $$\omega$$?

Accepted Answer

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

Question 13

If a rolling ball has both translational and rotational kinetic energy, which equation correctly expresses its total kinetic energy?

Accepted Answer

$$K_{total} = \frac{1}{2} m v^2$ + \frac{1}{2} I \$$omega^2$$

Question 14

Which of the following is the correct definition of elastic (spring) potential energy?

Accepted Answer

Energy stored when a spring or other elastic object is stretched

Question 15

A car is towed and its speed changes from $$v_i to$$ $$v_f. $$Which equation relates the work done to the change in kinetic energy?

Accepted Answer

$$W = \frac{1}{2} m v_f^2$ - \frac{1}{2} m v_i^2$

Question 16

Which of the following is the correct expression for gravitational potential energy for an object of mass $$m at $$height $$h$$ above the ground?

Accepted Answer

$$U_g = mgh$$

Question 17

Which of the following is true about the net work done on an object moving at constant speed in a straight line?

Accepted Answer

The net work is zero.

Question 18

Which of the following best describes thermal energy?

Accepted Answer

Sum of the kinetic and potential energies of all the molecules in an object

Question 19

A force $$\vec{F} is $$applied at an angle $$	heta to $$the horizontal and moves an object a distance $$d. If$$ $$	heta = 90^\circ$$, what is the work done by the force?

Accepted Answer

$$W = 0$$

Ch.10 Energy and Work: Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드