1. 1. Mike is cutting the grass using a human-powered lawn mower. He pushes the mower with a force of
45 N directed at an angle of 41° below the horizontal direction. Calculate the work that Mike does on
the mower in pushing it 9.1 m across the yard.
(a) 510 J
(b) 460 J
(c) 410 J
(d) 360 J
(e) 310 J
2. A 5.00-kg block of ice is sliding across a frozen pond at 2.00 m/s. A 7.60-N force is applied in the
direction of motion. After the ice block slides 15.0 m, the force is removed. The work done by the
applied force is
(a) −114 J.
(b) +114 J.
(c) −735 J.
(d) +735 J.
(e) +19.7 J.
3. Brenda carries an 8.0-kg suitcase as she walks 25 m along a horizontal walkway to her room at a
constant speed of 1.5 m/s. How much work does Brenda do in carrying her suitcase?
(a) zero joules
(b) 40 J
(c) 200 J
(d) 300 J
(e) 2000 J
4. Use the work-energy theorem to find the force required to accelerate an electron (m = 9.11 x 10−31
kg)
from rest to a speed of 1.50 x 107
m/s in a distance of 0.0125 m.
(a) 8.20 x 10−15
N
(b) 5.47 10−22
N
(c) 8.20 x 10−17
N
(d) 1.64 10−14
N
(e) 3.56 x 10−19
N
5. The kinetic energy of an 1100-kg truck is 4.6 105
J. What is the speed of the truck?
(a) 25 m/s
(b) 33 m/s
(c) 29 m/s
(d) 17 m/s
(e) 21 m/s
6. A 10.0-g bullet traveling horizontally at 755 m/s strikes a stationary target and stops after penetrating
14.5 cm into the target. What is the average force of the target on the bullet?
(a) 1.97 x 104
N
(b) 2.07 x 105
N
(c) 6.26 x 103
N
(d) 3.13 x 104
N
(e) 3.93 x 104
N
7. During the construction of a high rise building, 40-kg block is vertically lifted 20 meters from the
surface of the earth. To one significant figure, what is the change in the gravitational potential energy of
the block?
(a) +800 J
(b) -800 J
(c) +8000 J
(d) -8000 J
(e) zero joules
8. A 1500-kg elevator moves upward with constant speed through a vertical distance of 25 m. How much
work was done by the tension in the elevator cable?
(a) 990 J
(b) 8100 J
(c) 140 000 J
(d) 370 000 J
(e) 430 000 J
9. Larry’s gravitational potential energy is 1870 J as he sits 2.20 m above the ground in a sky diving
airplane. What is Larry’s gravitational potential energy when be begins to jump from the airplane at an
altitude of 923 m?
(a) 7.85 105
J
(b) 1.87 103
J
(c) 3.29 104
J
(d) 9.36 102
(e) 4.22 106
J
2. 10. A helicopter (m = 1250 kg) is cruising at a speed of 25.0 m/s at an altitude of 185 m. What is the total
mechanical energy of the helicopter?
(a) 3.91 x 105
J
(b) 2.66 x 106
J
(c) 2.27 x 106
J
(d) 6.18 x 105
J
(e) 1.88 x 106
J
11. A pebble rolls off the roof of Science Hall and falls vertically. Just before it reaches the ground, the
pebble’s speed is 17 m/s. Neglect air resistance and determine the height of Science Hall.
(a) 42 m
(b) 33 m
(c) 26 m
(d) 21 m
(e)15 m
12. The initial velocity of a 4.0-kg box is 11 m/s, due west. After the box slides 4.0 m horizontally, its
speed is 1.5 m/s. Determine the magnitude and the direction of the non-conservative force acting on the
box as it slides.
(a) 42 N, due west
(b) 120 N, due east
(c) 31 N, due east
(d) 59 N, due east
(e) 83 N, due west
13. An automobile approaches a barrier at a speed of 20 m/s along a level road. The driver locks the brakes
at a distance of 50 m from the barrier. What minimum coefficient of kinetic friction is required to stop
the automobile before it hits the barrier?
(a) 0.4
(b) 0.5
(c) 0.6
(d) 0.7
(e) 0.8
14. The kinetic energy of a car is 8 x 106
J as it travels along a horizontal road. How much power is
required to stop the car in 10 s?
(a) zero watts
(b) 8 x 104
W
(c) 8 x 105
W
(d) 8 x 106
W
(e)8 x 107
W
15. A 51-kg woman runs up a flight of stairs in 5.0 s. Her net upward displacement is 5.0 m.
Approximately, what average power did the woman exert while she was running?
(a) 5.0 kW
(b) 1.0 kW
(c) 0.75 kW
(d) 0.50 kW
(e) 0.25 kW
16. What power is needed to lift a 49-kg person a vertical distance of 5.0 m in 20.0 s?
(a) 12.5 W
(b) 25 W
(c) 60 W
(d) 120 W
(e) 210 W
17. A 100-kg cannon at rest contains a 10-kg cannon ball. When fired, the cannon ball leaves the cannon
with a speed of 90 m/s. What is the recoil speed of the cannon?
(a) 4.5 m/s
(b) 9 m/s
(c) 45 m/s
(d) 90 m/s
(e) zero m/s
18. While in Earth’s orbit, an 80-kg astronaut carrying a 20-kg tool kit is initially drifting toward a
stationary (to her) space shuttle at a speed of 2 m/s. If she throws the tool kit toward the shuttle with a
speed of 6 m/s as seen from the shuttle, her final speed is
(a) 1 m/s toward the shuttle.
(b) 1 m/s away from the shuttle.
(c) 2 m/s toward the shuttle.
(d) 4 m/s toward the shuttle.
(e) 6 m/s away from the shuttle.
3. 19. On an interplanetary mission, a 58.5-kg astronaut is floating toward the front of her ship at 0.15 m/s,
relative to the ship. She wishes to stop moving, relative to the ship. She decides to throw away the
2.50-kg book she’s carrying. What should the speed and direction of the book be to achieve her goal?
(a) 0.15 m/s, toward the front of the ship
(b) 3.5 m/s, toward the back of the ship
(c) 3.7 m/s, toward the front of the ship
(d) 0.30 m/s, toward the back of the ship
(e) 1.8 m/s, toward the front of the ship
20. Two cars of equal mass collide on a horizontal frictionless surface. Before the collision, car A is at
rest while car B has a constant velocity of 12 m/s. After the collision, the two bodies are stuck
together. What is the speed of the composite body (A + B) after the collision?
(a) 3.0 m/s
(b) 6.0 m/s
(c) 12 m/s
(d) 24 m/s
(e) 36 m/s
21. A 1000-kg car traveling east at 20 m/s collides with a 1500-kg car traveling west at 10 m/s. The cars
stick together after the collision. What is the common velocity of the cars after the collision?
(a) 16 m/s, east
(b) 6 m/s, west
(c) 4 m/s, east
(d) 2 m/s, east
(e) 1 m/s, west
22. A 0.10-kg cart traveling in the positive x direction at 10.0 m/s collides with a 0.30-kg cart at rest. The
collision is elastic. What is the velocity of the 0.10-kg cart after the collision?
(a) +2.5 m/s
(b) -2.5 m/s
(c) +5 m/s
(d) -5 m/s
(e) +3.3 m/s
23. A 2.5-kg ball and a 5.0-kg ball have an elastic collision. Before the collision, the 2.5-kg ball was at
rest and the other ball had a speed of 3.5 m/s. What is the kinetic energy of the 2.5-kg ball after the
collision?
(a) 1.7 J
(b) 3.4 J
(c) 8.1 J
(d) 14 J
(e) 27 J
24. During hockey practice, two pucks are sliding across the ice in the same direction. At one instant, a
0.18-kg puck is moving at 16 m/s while the other puck has a mass of 0.14 kg and a speed of 3.8 m/s.
What is the velocity of the center of mass of the two pucks?
(a) 5.0 m/s
(b) 7.0 m/s
(c) 9.0 m/s
(d) 11 m/s
(e) 13 m/s
25. Jennifer is walking at 1.63 m/s. If Jennifer weighs 583 N, what is the magnitude of her momentum?
(a) 97.0 kg m/s
(b) 137 kg m/s
(c) 68.6 kg m/s
(d) 672 kg m/s
(e) 951 kg m/s
26. A 1.0-kg ball has a velocity of 12 m/s downward just before it strikes the ground and bounces up with
a velocity of 12 m/s upward. What is the change in momentum of the ball?
(a) zero kg m/s
(b) 12 kg m/s, downward
(c) 12 kg m/s, upward
(d) 24 kg m/s, downward
(e) 24 kg m/s, upward
27. A projectile is launched with 200 kg m/s of momentum and 1000 J of kinetic energy. What is the
mass of the projectile?
(a) 5 kg
(b) 10 kg
(c) 20 kg
(d) 40 kg
(e) 50 kg
