Q: A car of mass $$m = 1200\ \mathrm{kg}$$ accelerates from rest to $$v = 25\ \mathrm{m/s} on a $$straight, level road. What is the change in its kinetic energy?

$$3.75 \times 10^5$\ \mathrm{J}$$

Q: A roller coaster car of mass $$500\ \mathrm{kg}$$ starts from rest at a height of $$20\ \mathrm{m}. $$Neglecting friction, what is its speed at the bottom of the track?

$$\sqrt{2 \times 9.8 \times 20} = 19.8\ \mathrm{m/s}$$

Question 1

A car of mass $$m = 1200\ \mathrm{kg}$$ accelerates from rest to $$v = 25\ \mathrm{m/s} on a $$straight, level road. What is the change in its kinetic energy?

Accepted Answer

$$3.75 	imes 10^5$\ \mathrm{J}$$

Question 2

Which of the following statements about conservative forces is correct?

Accepted Answer

The work done by a conservative force on a particle moving between two points is independent of the path taken.

Question 3

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

Accepted Answer

$$\sqrt{2gh}$$

Question 4

The elastic potential energy stored in a spring with spring constant $$k$$ and extension $$x is $$given by:

Accepted Answer

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

Question 5

A $$2\ \mathrm{kg}$$ object is lifted vertically by $$5\ \mathrm{m}. $$What is the increase in its gravitational potential energy? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$98\ \mathrm{J}$$

Question 6

Which equation correctly expresses the work-energy theorem?

Accepted Answer

$$W_{\mathrm{tot}} = K_2$ - K_1$ = \Delta K$$

Question 7

A $$10\ \mathrm{kg}$$ mass is attached to a spring with $$k = 200\ \mathrm{N/m}$$ and is compressed by $$0.2\ \mathrm{m}. $$What is the elastic potential energy stored in the spring?

Accepted Answer

$$4\ \mathrm{J}$$

Question 8

A satellite of mass $$m$$ orbits the Earth at a distance $$r$$ from the center of the Earth. What is the gravitational potential energy of the satellite-Earth system?

Accepted Answer

$$-\frac{G M_E m}{r}$$

Question 9

A block slides across a rough surface and comes to rest. Which statement best describes the energy transformation?

Accepted Answer

Mechanical energy is transformed into internal energy due to friction.

Question 10

A roller coaster car of mass $$500\ \mathrm{kg}$$ starts from rest at a height of $$20\ \mathrm{m}. $$Neglecting friction, what is its speed at the bottom of the track?

Accepted Answer

$$\sqrt{2 	imes 9.8 	imes 20} = 19.8\ \mathrm{m/s}$$

Question 11

Which of the following is NOT a conservative force?

Accepted Answer

Friction

Question 12

The escape velocity from a planet of mass $$M$$ and radius $$R is $$given by:

Accepted Answer

$$\sqrt{\frac{2GM}{R}}$$

Question 13

A $$24500\ \mathrm{kg}$$ jet lands on an aircraft carrier and is brought to rest from $$65\ \mathrm{m/s}$$ over a distance of $$96\ \mathrm{m}. $$What is the average force exerted by the arresting cable?

Accepted Answer

$$-538,020\ \mathrm{N}$$

Question 14

Which of the following best describes the total mechanical energy $$E of a $$system?

Accepted Answer

$$E = K + U$$

Question 15

A ball is thrown vertically upward with an initial speed $$v_0. $$Neglecting air resistance, which of the following statements is true at the highest point?

Accepted Answer

The kinetic energy is zero and the potential energy is maximum.

Question 16

Newton's law of universal gravitation states that the force between two masses $$m_1$$ and $$m_2$$ separated by a distance $$r is$$:

Accepted Answer

$$F = G \frac{m_1$ m_2$}{r^2$}$$

Question 17

A block of mass $$m is $$attached to a spring and oscillates on a frictionless surface. At maximum displacement, which energy is at its maximum?

Accepted Answer

Elastic potential energy

Question 18

A $$10\ \mathrm{kg}$$ ring slides down a frictionless vertical rod and compresses two springs (each $$k = 1000\ \mathrm{N/m}) by$$ $$0.3\ \mathrm{m}. If $$its speed at the top was $$2\ \mathrm{m/s}$$ and the compression at the top was $$0.1\ \mathrm{m}$$, what is the speed at the bottom?

Accepted Answer

$$5.1\ \mathrm{m/s}$$

Question 19

A block of mass $$20\ \mathrm{kg}$$ slides $$2\ \mathrm{m}$$ down a $$60^\circ$$ incline connected to a $$10\ \mathrm{kg}$$ block over a pulley. The coefficient of kinetic friction is $$0.20. $$What is the speed of block A after $$2\ \mathrm{m}$$?

Accepted Answer

$$4.7\ \mathrm{m/s}$$

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

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