Exercise Solution
Multiple-Choice: Circle the correct answer
The problem number refers to the chapter in which the topic is covered
2a. When is the average velocity
of an object equal to the instantaneous velocity?
A) always
B) never
C) only when the velocity is constant
D) only when the velocity is increasing at a constant rate
Answer: C
2b. A new car manufacturer
advertises that their car can go "from zero to sixty in 8 s". This is a
description of
A) average speed.
B) instantaneous speed.
C) average acceleration.
D) instantaneous acceleration.
Answer: C
3a. Two vectors, of magnitudes
20 and 50, are added. Which one
of the following is a possible
answer for the magnitude of the resultant?
A) 10
B) 20
C) 40
D) 80
Answer: C
3b. Three forces, each having a
magnitude of 30 N, pull on an object in directions that are 120°
apart from each other. Make a
statement concerning the resultant force.
A) The resultant force is zero.
B) The resultant force is greater than 30 N.
C) The resultant force is equal to 30 N.
D) The resultant force is less than 30 N.
Answer: A
4a) In the absence of an
external force, a moving object will
A) stop immediately.
B) slow down and eventually come to a stop.
C) go faster and faster.
D) move with constant velocity.
Answer: D
4b) When the rocket engines on a
starship are suddenly turned off, while traveling in empty
space, the starship will
A) stop immediately.
B) slowly slow down, and then stop.
C) go faster and faster.
D) move with constant speed.
Answer: D
5a) When an object experiences
uniform circular motion, the direction of the acceleration is
A) in the same direction as the velocity vector.
B) in the opposite direction of the velocity vector.
C) is directed toward the center of the circular path.
D) is directed away from the center of the circular path.
Answer: C
5b) Consider a particle moving
with constant speed such that its acceleration of constant
magnitude is always perpendicular to its velocity.
A) It is moving in a straight line.
B) It is moving in a circle.
C) It is moving in a parabola.
D) None of the above is definitely true all of the time.
Answer: B
6a) If you push twice as hard
against a stationary brick wall, the amount of work you do
A) doubles.
B) is cut in half.
C) remains constant but non-zero.
D) remains constant at zero.
Answer: D
6b) A 50-N object was lifted 2.0
m vertically and is being held there.
How much work is being
done in
holding the box in this position?
A) more than 100 J
B) 100 J
C) less than 100 J, but more than 0 J
D) 0 J
Answer: D
7a) A sailboat of mass m is
moving with a momentum p. How
would you represent its kinetic
energy in terms of these two quantities?
A) p2/(2m)
B) 1/2 mp2
C) mp
D) mp/2
Answer: A
7b) If you pitch a baseball with
twice the kinetic energy you gave it in the previous pitch, the
magnitude of its momentum is
A) the same.
B) 1.41 times as much.
C) doubled.
D) 4 times as much.
Answer: B
8a) A boy and a girl are riding
on a merry-go-round which is turning at a constant rate.
The boy
is near
the outer edge, and the girl is closer to the center.
Who has the greater angular
displacement?
A) the boy
B) the girl
C) Both have the same non-zero angular displacement.
D) Both have zero angular displacement.
Answer: C
8b) A boy and a girl are riding
on a merry-go-round which is turning at a constant rate.
The boy
is near the outer edge, and the girl is closer to the center.
Who has the greater angular
speed?
A) the boy
B) the girl
C) Both have the same non-zero angular velocity.
D) Both have zero angular velocity.
Answer: C
9a) A heavy boy and a light girl
are balanced on a massless seesaw.
If they both move forward
so
that they are one-half their original distance from the pivot point, what
will happen to the
seesaw?
A) The side the boy is sitting on will tilt downward.
B) The side the girl is sitting on will tilt downward.
C) Nothing, the seesaw will still be balanced.
D) It is impossible to say without knowing the masses and the distances.
Answer: C
9b) A sphere hanging freely from
a cord is in
A) stable equilibrium.
B) unstable equilibrium.
C) neutral equilibrium.
D) positive equilibrium.
Answer: A
10a) Density is
A) proportional to both mass and volume.
B) proportional to mass and inversely proportional to volume.
C) inversely proportional to mass and proportional to volume.
D) inversely proportional to both mass and volume.
Answer: B
10b) Pressure is
A) proportional to both force and area.
B) proportional to force and inversely proportional to area.
C) inversely proportional to force and proportional to area.
D) inversely proportional to both force and area.
Answer: B
13a Which temperature scale
never gives negative temperatures?
A) Kelvin
B) Fahrenheit
C) Celsius
D) all of the above
Answer: A
13b) If the pressure acting on
an ideal gas at constant temperature is tripled, its volume is
A) reduced to one-third.
B) increased by a factor of three.
C) increased by a factor of two.
D) reduced to one-half.
Answer: A
14a) An ideal gas at STP is
first compressed until its volume is half the initial volume, and then
it is allowed to expand until its pressure is half the initial
pressure. All of this is done
while
holding the temperature constant.
If the initial internal energy of the gas is U, the final
internal energy of the gas will be
A) U.
B) U/3.
C) U/2.
D) 2U.
Answer: A
14b) An ideal gas with internal
energy U at 200°C is heated to 400°C.
Its internal energy then
will be
A) still U.
B) 2 U.
C) 1.4 U.
D) 1.2 U.
Answer: C