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Physics 101
Test 2
23 May 2016
Multiple Choice. Choose the best answer to each question.
____1.
A 900 kg Chevy truck has 27,000 kg m/s of momentum. How fast is it moving?
a) 30 m/s
b) 3 m/s
c) .0333 m/s
d) 0.333 m/s
____2.
My head hurts less when hitting an airbag than when hitting the windshield because
a) lesser time to stop
b) lower impulse when hitting airbag
c) greater change in momentum for airbag d) impact force is decreased
____3.
A 10 kg chunk of putty moving at 3 m/s collides and sticks to a 5kg bowling ball initially at
rest. The bowling ball and putty then move with a speed of
a) 0 m/s
b) 1 m/s
c) 2 m/s
d) 3 m/s
____4.
Ok, so Superman (80 kg) throws a 80,000 kg asteroid towards the sun at 2 m/s. If they
both started at rest, how fast does Superman travel backwards after the throw?
a) 2 m/s
b) 200 m/s c) 200 m/s d) 2000 m/s e) 0 m/s
____5.
Momentum is measured in units of
a) kg m/s2
b) kg s/m
c) kg m2/s
d) kg m/s
____6.
Two identical freight trains are moving towards each other on the tracks at a high rate of
speed. What is the total momentum of that system?
a) 10 kg m/s b) 0 kg m/s c) 1000 kg m/s
d) not enough info
____7.
How long would it take to stop a 1500 kg racecar moving at 10 m/s using a braking force
of 4000 N?
a) 0.375 s b) 3.75 s
c) 37.5 s
d) 375 s
____8.
How much potential energy does my 200 kg sister have sitting in a tree 3 m off the
ground?
a) 6000 Joules
b) 600 Joules
c) 60 Joules
d) 2000 Joules
____9.
If I push on a 50 kg sled with 100 N of force for 10 m, how fast is it going if it started from
rest?
a) 20 m/s
b) 10.4 m/s
c) 6.3 m/s
d) 40 m/s
____10.
How long could I run a 1500 W hairdryer with 475,000 joules of energy?
a) .0031 seconds b) 7.13x108 seconds
c) 3600 seconds
d) 317 seconds
Use the picture to the right for questions 11-15.
Ok, Scheller drops his 200 kg sister from rest off the leaning
tower of Haubstadt, which stands 20 meters high.
____11.
What is her kinetic energy at the top of the tower?
a) 0 J
b) 4000 J
c) 20,000 J
d) 40,000 J
____12.
What is her potential energy at the top of the tower?
a) 0 J
b) 4000 J
c) 20,000 J
d) 40,000 J
____13.
What is her kinetic energy at a height of 5 m from the ground?
a) 1000 J
b) 10,000 J
c) 3000 J
d) 30,000 J
____14.
What is her potential energy at a height of 5 m from the ground?
a) 1000 J
b) 10,000 J
c) 3000 J
d) 30,000 J
____15.
What is her velocity at a height of 5 m from the ground?
a) 10 m/s
b) 15.3 m/s c) 17.3 m/s
d) 20 m/s
____16.
Which requires more work: lifting a 50 kg sack vertically 2 meters or lifting a 25 kg sack
vertically 5 meters?
a) lifting the 50 kg sack
b) lifting the 25 kg sack
c) both require same work
____17.
An object that has potential energy must be
a) moving
b) falling
c) at an elevated position
20m
d) at rest
____18.
A 1 kg mass has 40 J of potential energy with respect to the ground. How far is it located
above the ground?
a) 1 m
b) 2 m
c) 3 m
d) 4 m
____19.
An engine that is 40% efficient uses how much energy per cycle when it performs 300
Joules of work?
a) 750 Joules
b) .133 Joules
c) 120 Joules
d) 75 Joules
____20.
My son Nick is on the infamous merry-go-round at the playground rotating at 10
revolutions each minute. If he walks inward, making the inertia go down by 3, how fast
will the merry-go-round rotate then?
a) same, 10 rpm
b) 3.33 rpm
c) 30 rpm
d) depends on his mass
____21.
If a 20 kg child sits 2 m from the center of a see-saw, how far from the center must a 40
kg child sit on the other side to balance the see-saw?
a) 4 m
b) 2 m
c) 1 m
d) 0.5 m
____22.
When a twirling ice skater extends her arms outward, she is
a) increasing rotational inertia, decreasing speed
b) decreasing rotational inertia, increasing speed
c) increasing rotational inertia, increasing speed
d) decreasing rotational inertia, decreasing speed
____23.
Two masses 3 meters from each other exert a gravitational force of 300 Newtons on each
other. If those same two masses were brought closer to a distance of 1 m from each
other, what would be the force of attraction between them?
a) 100 N
b) 300 N
c) 2700 N
d) 8100 N
____24.
For a satellite orbiting the earth, what is providing the centripetal force necessary for it to
complete its orbits?
a) friction
b) inertia
c) gravity
d) momentum
____25.
Centripetal forces that make objects move in circles do so by
a) changing the speed of the object in a turn
b) changing the speed and direction of the object in a turn
c) changing the direction of the object in a turn
d) all of these
1a
13d
2d
14b
3c
15c
4d
16b
5d
17c
6b
18d
7b
19a
8a
20c
9c
21c
10a
22a
11a
23c
12d
24c
25c