Collisions

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```					Collisions
100 points-Running at 2.0 m/s, Bruce, the 45.0 quarterback, collides with Biff, the 90.0 kg tackle, who is
traveling at 7.0 m/s in the other direction. Upon collision, Biff continues to travel forward at 1.0 m/s. How fast
is Bruce knocked backwards?
a. 10.0 m/s
b. –10.0 m/s
c. 15.5 m/s
d. –15.5 m/s

200 points-Anthony and Sissy are participating in the “Roll-a-Rama” rollerskating dance championship. While
75.0 kg Anthony rollerskates backwards at 3.0 m/s, 60.0 kg Sissy jumps into his arms with a velocity of 5.0 m/s
in the same direction. A) How fast does the pair roll backwards together? B) If Anthony is skating toward
Sissy when she jumps, would their combined final velocity be larger or smaller than your answer to part a?
Why?
a. 1.2 m/s
b. 2.4 m/s
c. 3.9 m/s
d. 4.7 m/s

300 points-Physics teacher, Mr. McKee, shoots a .22 caliber rifle at a 0.30 kg block of wood. The rifle and the
wood are mounted on carts that sit on an air track so that friction is negligible. The 6.0 kg gun fires a 0.020 kg
bullet with a speed of 200. m/s. A) What is the final velocity of the block of wood with the bullet lodged
inside?
a. 12.5 m/s
b. 18.3 m/s
c. 24.6 m/s
d. 35.8 m/s

400 points-A 620. kg moose stands in the middle of the railroad tracks, frozen by the lights of an oncoming
10,000. kg locomotive that is traveling at 10.0 m/s. The engineer sees the moose but is unable to stop the train
in time and the moose rides down the track sitting on the cowcatcher. What is the new combined velocity of the
locomotive and the moose?
a. 5.45 m/s
b. 9.42 m/s
c. 13.2 m/s
d. 18.7 m/s

500 points-In Sharkey’s Billiard Academy, Maurice is waiting to make his last shot. He notices that the cue
ball is lined up for a perfect head-on collision. Each of the billiard balls has a mass of 0.0800 kg and the cue
ball comes to a complete stop upon making impact with the 8 ball. Suppose Maurice hits the cue ball by
exerting a force of 180. N for 5.00 x 10-3 s, and it knocks head-on into the 8 ball. Calculate the resulting
velocity of the 8 ball.
a. –6.250 m/s
b. 6.250 m/s
c. –11.25 m/s
d. 11.25 m/s
Rotation & Circular Motion

100 points-The platter of a hard drive of a computer rotates at 7200 rpm. What is the angular velocity of the

200 points-Luigi twirls a round piece of pizza dough overhead with a frequency of 60. revolutions per minute.
Find the linear speed of a piece of pepperoni stuck on the dough 10. cm from the pizza’s center.
a. 0.63 m/s
b. 0.95 m/s
c. 19 m/s
d. 38 m/s

300 points-Jessica is riding on a merry-go-round on an outer horse that sits at a distance of 8.0 m from the
center of the ride. Jessica’s sister, Julie, is on an inner horse located 6.0 m from the ride’s center. The merry-
go-round turns around once every 40.0 s. What is the centripetal acceleration of Julie and her horse?
a. 0.0031 m/s2
b. 0.0041 m/s2
c. 0.11 m/s2
d. 0.15 m/s2

400 points-A child swings a yo-yo above his head in a circle that is parallel with the floor. If the diameter of
the circle is 140 cm and he maintains an angular velocity of 20. revolutions in a time of 16.3 seconds-what is
the tangential velocity of the yo-yo at any point on the path?
a. 0.86 m/s
b. 1.2 m/s
c. 3.7 m/s
d. 5.4 m/s

500 points-At the Fermilab particle accelerator in Batavia, Illinois, protons are accelerated by electromagnets
around a circular chamber of 1.00-km radius to speeds near the speed of light before colliding with a target to
produce enormous amounts of energy. If a proton is traveling at 10% the speed of light, how much centripetal
force is exerted by the electromagnets? (Hint: the speed of light is 3.00 x 108 m/s, the mass of a proton is 1.67
x 10-27 kg)
a. 5.01 x10-23 N
b. 1.50 x 10-15 N
c. 1.50 x 10-13 N
d. 9 x 1011 N
Work, Energy, Power

100 points-If a 1000. kg roller coaster leaves the top of a 50.0 m peak from rest, how fast is it traveling when it
reaches the ground? (Assume the coaster is frictionless.)
a. 22.1 m/s
b. 31.3 m/s
c. 490 m/s
d. 980 m/s

200 points-The same roller coaster travels up to the top of a 25 m peak after the above problem. What is its
speed at this point compared to its speed in problem 3?
a. 1/2
b. 2
c. 2
d. 4

300 points-A 102 kg man climbs a 5.0 m high staircase at a constant speed. How much work does he do?
a. 510 J
b. 49 J
c. 5000 J
d. 2500 J

400 points-Atlas and Hercules, two carnival sideshow strong men, each lift two 200. kg barbells 2.00 m off the
ground. Atlas lifts his barbells in 1.00 s and Hercules lifts his in 3.00 s. Calculate Hercules’ power.
a. 1310 W
b. 1950 W
c. 2610 W
d. 7840 W

500 points-Brittany is changing the tire of her car on a steep hill 20.0 m high. She trips and drops the 10.0 kg
spare tire, which rolls down the hill with an initial speed of 2.00 m/s. What is the speed of the tire at the top of
the next hill, which is 5.00 m high?
a. 12 m/s
b. 15 m/s
c. 17 m/s
d. 20. m/s
Work & Energy on Inclined Plane

100 points-A 1774 kg car starts from rest at the top of a driveway 6.17 m long which is sloped at an angle of 20
degrees with the horizontal. If a frictional force of 3714 N impedes the motion of the car, find the speed (in
m/s) of the car at the bottom of the driveway.
a. 1.99 m/s
b. 2.99 m/s
c. 3.99 m/s
d. 4.99 m/s

200 points-A 2.21 kg block is projected up a 30 degree incline with an initial speed of 6.44 m/s at the bottom.
The coefficient of kinetic friction between the block and the incline is 0.744. Find the distance (in m) the block
will travel up the incline before coming to rest.
a. 1 m
b. 2 m
c. 3 m
d. 4 m

300 points-In a circus performance, a monkey on a sled is given an initial speed of 4.9 m/s up a 20 degree
incline. The combined mass of the monkey and the sled is 28 kg, and the coefficient of kinetic friction between
the sled and incline is 0.258. How far (in m) will the sled move up the incline?
a. 1 m
b. 2 m
c. 3 m
d. 4 m

400 points-A child starts from rest at the top of a slide of height 8.92 m. If she reaches the bottom with a speed
of 9.02 m/s, what percentage of her total energy at the top of the slide is “lost” as a result of friction?
a. 22.4%
b. 53.5%
c. 64.7%
d. 87.4%

500 points-(Not on an incline, but I wanted to get this question in here somewhere!) If a 65.3 kg man jumps
off a 1.23 m high table and lands with his knees and ankles locked, the only cushion for his fall is then an
approximate 0.443 cm “give” in the pads of his shoes. Calculate the force (in Newtons) exerted on him by the
ground in this situation. (Assume there is no energy converted into friction for this problem.)
a. 135,000 N
b. 178,000 N
c. 203,000 N
d. 230,000 N
Universal Gravitation
100 points-Calculate the attractive force between Earth and a spacecraft 12,800 km above the surface of the
Earth if its mass is 1350 kg. Mass of Earth is 5.98 x 1024 kg.
a. 3290 N
b. 4.21 x 1010 N
c. 4.21 x 1013 N
d. 4.83 x 1014 N

200 points-If John Glenn weighed 640 N on Earth’s surface, how much would he have weighed if his Mercury
spacecraft had (hypothetically) remained at twice the distance from the center of the Earth? (Hint: radius of
Earth is 6378 km.) Mass of Earth is 5.98 x 1024 kg.
a. 160 N
b. 1560 N
c. 6.37 x 108 N
d. 6.28 x 109 N

300 points-If two people are sitting on a bench (m1=50.0 kg, m2=75.0 kg) exerting a gravitational force of 1.00
x 10-6 N on each other, what is the distance between them?
a. 0.250 m
b. 0.500 m
c. 192,000 m
d. 3.68 x 1010 m

400 points-Our galaxy, the Milky Way, contains approximately 4.0 x 1011 stars with an average mass of 2.0 x
1030 kg each. How far away is the Milky Way from our nearest neighbor, the Andromeda Galaxy, if
Andromeda contains roughly the same number of stars and attracts the Milky Way with a gravitational force of
2.4 x 1030 N?
a. 45.8 m
b. 4.2 x 1021 m
c. 1.1 x 1032 m
d. 1.8 x 1043 m

500 points-Astrologers claim that your personality traits are determined by the positions of the planets in
relation to you at birth. Scientists argue that these gravitational effects are so small that they are totally
insignificant. Compare the gravitational attraction between a baby (mass 8 pounds) and Mars to the
gravitational attraction between the same baby and their 70.0 kg doctor at the moment of their birth, if the
doctor stands 0.500 m away. (MM=6.42 x 1023 kg, dE to M=7.83 x 1010 m. This is the average distance between
Earth and Mars. This distance varies as the two planets orbit the sun.)
a. Attraction between baby and Mars=3 x 10-8 N, between baby and doctor=4 x 10-8 N
b. Attraction between baby and Mars=3 x 10-8 N, between baby and doctor=7 x 10-8 N
c. Attraction between baby and Mars=6 x 10-8 N, between baby and doctor=4 x 10-8 N
d. Attraction between baby and Mars=6 x 10-8 N, between baby and doctor=7 x 10-8 N
Impulse & Momentum

100 points-A 77.8 kg diver steps off a 12.44 meter tower and drops straight down into the water. If he goes no further
than 5.14 m beneath the surface of the water, determine the resistance force (in Newtons) exerted on the diver by the
water.
a. 0 N
b. 1840 N
c. 5540 N
d. 9480 N

200 points-A tennis ball traveling at 10.0 m/s is returned by Chris Evert. It leaves her racket with a speed of
36.0 m/s in the opposite direction from which it came. A) What is the change in momentum of the tennis ball?
a. 1.45 kgm/s
b. 1.99 kgm/s
c. 2.34 kgm/s
d. 2.76 kgm/s

300 points-Rhonda, who has a mass of 60.0 kg, is riding at 25.0 m/s in her sports car when she must suddenly
slam on the brakes to avoid hitting a dog crossing the road. She is wearing her seatbelt, which brings her body
to a stop in 0.400 s. a) What average force did the seatbelt exert on her?
a. –2560 N
b. –3750 N
c. –4750 N
d. –5530 N

400 points-If 240 million people in the United States jumped up in the air simultaneously, pushing off the earth
with an average force of 800. N each for a time of 0.10 s, what would be the rebound velocity of the 5.98 x 1024
a. 1.1 x 10-12 m/s
b. 2.8 x 10-12 m/s
c. 3.2 x 10-12 m/s
d. 4.5 x 10-12 m/s

500 points-During an autumn storm, a 0.012 kg hail stone traveling at 20.0 m/s made a 0.20 cm deep dent in the
hood of Casey’s new car. What average force did the car exert to stop the damaging hail stone?
a. 1200 N
b. 2500 N
c. 3700 N
d. 4900 N

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