Momentum and Energy Multiple Choice Section.
Make no marks. Bubble in best answer on Scantron sheet.
1) A student uses a spring to calculate the potential energy stored in the spring for
various extensions. A straight line graph results from a plot of E p vs. x2. The student
calculates the slope of the best fit line. What extra step must she do to determine the
spring constant?
A) Divide the slope by 2.
B) Divide the slope by x2.
C) Multiply the slope by 2.
D) Multiply the slope by x2.
2) In simple harmonic motion, a mass bounces on the end of an ideal spring. At point A,
the mass is at maximum extension, at point B the mass is at the equilibrium point and
at point C, the mass is between point A and B. If we can ignore the effects of gravity, the
total energy for each point A, B, and C is found respectively as:
A) Ek, Eel and Ek + Eel
B) Ek + Eel, Eel and Ek
C) Eel, Ek, Eel
D) Eel, Ek, Ek + Eel
3) A 12.0 kg mass hangs at rest on a spring near the Earth’s surface. If the spring has a
displacement of 12.0 cm, what is the spring constant?
A) 1.0 N/m
B) 9.81 N/m
C) 10.0 N/m
D) 981 N/m
4) A 125 g mass oscillates in simple harmonic motion on the end of a spring (k= 5.00
N/m). What is the period of oscillation (as a factor of π), in seconds?
A) 10.0 π
B) 0.316 π
C) 50.0 π
D) 0.0500 π
5) The total energy of a 5.00 kg mass undergoing SHM is 62.5 J. What is the maximum
velocity of the 5.00 kg mass?
A) ± 5.00 ms-1
B) ± 25.0 ms-1
C) ± 2.50 ms-1
D) ± unknown
Use the following information to answer the next two questions.
On July 16, 1994, one of the fragments of comet Shoemaker-Levy 9 entered Jupiter’s
atmosphere travelling at 60.0 km/s. As a comet fragment approaches a planet and
before it enters the atmosphere, it gains kinetic energy.
As the fragment approached Jupiter’s surface, the atmosphere became too dense for the
fragment to push through. The fragment’s tremendous kinetic energy was dissipated in
an enormous explosion. The mass of Jupiter is 318 times that of Earth. The mass of the
comet was 6000. kg.
6) The kinetic energy of the comet fragment as it entered into Jupiter’s atmosphere was:
A) 1.08 x 107 J
B) 1.80 x 108 J
C) 1.80 x 1011 J
D) 1.08 x 1013 J
7) When the comet fragment’s kinetic energy was dissipated in the explosion, most of
the energy was converted to:
A) potential and kinetic energy
B) chemical energy only
C) light and heat
D) light only
8) Kathryn is diving from a tower 10.0 m above the water. When she is 5.0 m above the
surface of the water, her:
A) momentum and kinetic energy are about equal
B) velocity is half of the velocity she will have when she touches the water
C) potential energy, with respect to the water, and her momentum are about equal
D) potential energy, with respect to the water, and her kinetic energy are about equal
9) Which of the following are scalar quantities:
A) kinetic energy and potential energy
B) kinetic energy and momentum
C) potential energy and force
D) momentum and force
10) A space shuttle astronaut has a mass of 110 kg with her space suit on. She picks
up a full can of spray paint with a mass of 20. kg. If she starts at rest (relative to the
space shuttle) and releases 3.0 kg of spray at 15 m/s directly in front of her centre of
mass to avoid rotation, what is her speed (relative to the shuttle) when she has stopped
spraying?
A) 0.35 m/s
B) 0.41 m/s
C) 2.3 m/s
D) 2.5 m/s
11) A single stationary railway car is bumped by a five-car train moving at 9.3 km/h.
The six cars move off together after the collision. Assuming the masses of all the cars
are the same, the speed of the new six-car train immediately after impact is:
A) 7.8 km/h
B) 8.5 km/h
C) 9.3 km/h
D) 11 km/h
12) Two railway cars, each of mass m, are approaching each other on a straight line
with the same constant speed v. Their total kinetic energy E k and total momentum p
are:
A) Ek = mv2, p = 2mv
B) Ek = (½)mv2, p = mv
C) Ek = mv2, p = 0
D) Ek = 0, p = 2mv
13) A 47.0 g golf ball is hit with an initial velocity of 70.0 m/s at an angle of 30.0 o up
from the horizontal. The vertical component of the ball’s momentum is:
A) 1.65 kgm/s
B) 2.85 kgm/s
C) 3.29 kgm/s
D) 6.58 kgm/s
14) Bumper cars are useful for momentum studies. Car X has a mass of 1.25 x 10 2 kg
and travels at 2.25 m/s [E] and Car Y has a mass of 1.61 x 10 2 kg and travels at 1.30
m/s [W]. If after the collision Car Y is travelling at 0.526 m/s [E], the velocity of Car X
immediately after impact is:
A) 0.102 m/s [W]
B) 3.25 m/s [E]
C) 4.60 m/s [E]
D) 10.2 m/s [W]
15) In an inelastic collision, the energy that appears to be missing is converted into:
A) sound and momentum
B) force and momentum
C) sound and heat
D) heat and force
16) A 1000 kg car travelling east on an icy road hits a parked truck with a mass of 1500
kg. Immediately after the collision, the car moves off at an angle of 20.0o N of E and the
truck moves off at 45.0o S of E. Police use which physics principles to determine the
resultant speed of the truck:
A) conservation of kinetic energy but not conservation of momentum.
B) conservation of momentum but not conservation of kinetic energy
C) both conservation of momentum and conservation of kinetic energy
D) neither conservation of momentum nor conservation of kinetic energy
17) The SI units for impulse may be written as:
A) kgm2/s2
B) kgm/s
C) kgm2/s
D) kgm/s2
18) The physical quantity that can have the same unit as impulse is:
A) force
B) work
C) power
D) momentum
19) A stationary bomb explodes in a street. Three pieces of debris with the same masses
fly off in different directions. One piece flew East at 20.0 m/s, while a second piece flew
Southeast at 30.0 m/s. Where would investigators look for the third piece?
A) 27.0o W of N
B) 27.0 o S of E
C) 22.5 o S of W
D) 22.5 o N of E
20) An archer requires 130. N to pull a bow to 70.0 cm. The maximum speed of a 20.6 g
arrow is:
A) 66.5 m/s
B) 94.0 m/s
C) 4.42 x 103 m/s
D) 8.83 x 103 m/s
Use the following information to answer the next 5 questions:
Deployment of Air Bags
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S
N
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Air bags are designed to deploy when a car, moving at a minimum speed of
18 km/h, comes to a crashing stop. The impact sensor, also moving at 18
km/h. consists of a small steel ball of 0.050 kg, which is held in position
by a magnet, as shown. On impact, the ball breaks free in 1.00 ms and
slides within a cylinder. The ball makes contact with the 2 electrodes at the
other end, which activates the airbag.
21) What is the magnitude of the force required to break away from the magnet?
A) 2.5 x 105 N
B) 1.3 x 105 N
C) 2.5 x 102 N
D) 1.3 x 102 N
22) If the car was moving at 18 km/h, the maximum speed of the ball immediately after
impact would be:
A) 62 m/s
B) 18 m/s
C) 5.0 m/s
D) 0 m/s
23) If the car was initially moving at 18 km/h, the driver had a mass of 70. kg, and the
air bag stopped him in 0.10 s, the magnitude of the force acting on the driver during the
deceleration would be:
A) 1.3 x 104 N
B) 3.5 x 103 N
C) 1.3 x 103 N
D) 3.5 x 102 N
24) The entire process, from impact to air bag inflation, takes less than 3.0 ms. During
this same time, how far forward would a passenger who was not wearing a seatbelt
move?
A) 1.5 cm
B) 1.8 cm
C) 5.0 m
D) 0 m
25) The main purpose of an air bag system is to:
A) shorten the stopping time of the driver’s head and upper body as they move forward.
B) act as a cushion and shield for glass and flying debris.
C) lengthen the stopping time of the driver’s head and upper body as they move
forward.
D) prevent the steering wheel from collapsing.