Unit 5 | Work & Energy Review

If you push twice as hard against a stationary brick wall, the amount of work you do...

• Doubles

• Is cut in half

• Remains constant, but non-zero

• Remains constant at zero

A container of water is lifted vertically 3.0 m then returned to its original position. If the total weight is 30 N, how much work was done?

• 45 J

• 90 J

• 180 J

• No work was done

The area under the curve, on a Force versus Position (F vs. x) graph, represents what physical value?

• Work

• Kinetic Energy

• Power

• Potential Energy

A truck weighs twice as much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of the car?

• All that can be said is that the truck has more kinetic energy.

• The truck has twice the kinetic energy of the car.

• The truck has 4 times the kinetic energy of the car.

• The truck has 8 times the kinetic energy of the car.

A rubber ball with mass 0.20 kg is dropped vertically from a height of 1.5 m above a floor. The ball bounces off of the floor, and during the bounce 0.60 J of energy is dissipated. What is the maximum height of the ball after the bounce?

• 0.30 m

• 0.90 m

• 1.19 m

• 1.51 m

A sled slides down a hill with friction between the sled and hill but negligible air resistance.

Which of the following must be correct about the resulting change in energy of the sled-Earth

system?

• The sum of the kinetic energy and the gravitational potential energy changes by an amount equal to the energy dissipated by friction.

• The gravitational potential energy decreases and the kinetic energy is constant.

• The decrease in the gravitational potential energy is equal to the increase in kinetic energy.

• The gravitational potential energy and the kinetic energy must both decrease.

A student lifts a 22 N physics book up in the air a distance of 2.2 m, at a constant velocity of 0.50 m/s. How much work has the student done?

• 46.2 J

• 48.4 J

• 474.8 W

• 48.4 W

A 5.0 kg block moves in a straight line on a horizontal frictionless surface under the influence of a force that varies with position. Calculate the amount of work done by the force as the block moves from the x = 0 m to x = 10.0 m.

• -2 J

• -8 J

• 12 J

• 26 J

A 300-Watt electric wheelchair has a mass of 50 kg, and carries its 50 kg occupant at constant velocity up a long ramp. About how much time does it take the wheelchair to reach the top of the 10-meter high ramp?

• 32.7 s

• 16.35 s

• 3.24 s

• 0 s

A roller coaster car of mass m = 200 kg is released from rest at the top of a 60 m high hill, and rolls with negligible friction down the hill, through a circular loop of radius 20 m, and along a horizontal track. What is the velocity of the car at position B?

• 21.5 m/s

• 34.3 m/s

• 54 m/s

• 81 m/s