REVIEW PHYSICS CHAPTER 3

A 50-N object was lifted 2.0 m vertically and is being held there. How much work is being done in holding the box in this position? Select one: a. 100 J b. less than 100 J, but more than 0 J c. 0 J d. more than 100 J

The correct answer is: 0 J

A worker does 25 J of work lifting a bucket, then sets the bucket back down in the same place. What is the total net work done on the bucket? Select one: a. 50 J b. 25 J c. 0 J d. -25 J

The correct answer is: 0 J

An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy? Select one: a. 1/2 b. 2 c. 4 d. 1/4

The correct answer is: 1/4

A roller coaster starts at a point 30 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip? Select one: a. 14 m/s b. 16 m/s c. 18 m/s d. 20 m/s

The correct answer is: 18 m/s

A 0.200-kg mass attached to the end of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring will be Select one: a. the same. b. twice as much. c. 4 times as much. d. 3 times as much.

The correct answer is: 4 times as much.

If the displacement of a horizontal mass-spring system was doubled, the elastic potential energy in the system would change by a factor of Select one: a. 2. b. 1/4. c. 1/2. d. 4

The correct answer is: 4.

In which of the following scenarios is no net work done? Select one: a. A car accelerates down a hill. b. A car decelerates on a flat road. c. A car travels at constant speed on a flat road. d. A car decelerates as it travels up a hill.

The correct answer is: A car travels at constant speed on a flat road.

A ball falls from the top of a building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building? Select one: a. K is less than U. b. K is equal to U. c. It is impossible to tell. d. K is greater than U.

The correct answer is: K is less than U.

What are the units for a spring constant? Select one: a. N m b. m c. N/m d. N

The correct answer is: N/m

Can work be done on a system if there is no motion? Select one: a. Yes, if an outside force is provided. b. No, because of the way work is defined. c. Yes, since motion is only relative. d. No, since a system which is not moving has no energy.

The correct answer is: No, because of the way work is defined.

A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a greater height? Select one: a. The heavy object, because it has greater kinetic energy. b. They both slide to the same height. c. The lightweight object, because it weighs less. d. cannot be determined from the information given

The correct answer is: They both slide to the same height.

You throw a ball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down. Select one: a. Work is - on the way up and + on the way down. b. Work is - on the way up and - on the way down. c. Work is + on the way up and - on the way down. d. Work is + on the way up and + on the way down.

The correct answer is: Work is - on the way up and + on the way down.

Is it possible for a system to have negative potential energy? Select one: a. Yes, as long as the total energy is positive. b. Yes, since the choice of the zero of potential energy is arbitrary. c. No, because this would have no physical meaning. d. No, because the kinetic energy of a system must equal its potential energy.

The correct answer is: Yes, since the choice of the zero of potential energy is arbitrary.

Gravitational potential energy is always measured in relation to Select one: a. mechanical energy. b. kinetic energy. c. a zero level. d. total potential energy.

The correct answer is: a zero level.

What is the correct unit of power expressed in SI units? Select one: a. kg m/s b. kg m/s c. kg m /s d. kg m /s

The correct answer is: kg m2 /s3

The main difference between kinetic energy and potential energy is that Select one: a. although both energies involve motion, only kinetic energy involves position. b. kinetic energy involves position, and potential energy involves motion. c. kinetic energy involves motion, and potential energy involves position. d. although both energies involve position, only potential energy involves motion.

The correct answer is: kinetic energy involves motion, and potential energy involves position

Which of the following energy forms is associated with an object due to its position? Select one: a. kinetic energy b. positional energy c. potential energy d. total energy

The correct answer is: potential energy

If the sign of work is negative, Select one: a. the displacement is in the same direction as the force. b. the displacement is perpendicular to the force. c. the displacement is in the direction opposite the force. d. no work is done.

The correct answer is: the displacement is in the direction opposite the force.

The quantity mgh is Select one: a. the gravitational potential energy of the object. b. the work done on the object by the force. c. the kinetic energy of the object. d. the power supplied to the object by the force.

The correct answer is: the gravitational potential energy of the object

Of the following, which is not a unit of power? Select one: a. newton-meter/second b. watt/second c. watt d. joule/second

The correct answer is: watt/second