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Dynamics Test Bank
1) If a = 2d/t2, solve for t2.
t2 =
2) If d = at2/2, solve for 2.
2=
3) 2.2 lb / 1 kg = w lb / x kg. Solve for x.
x kg =
4) 8 km/5 mi = p km/x mi. x mi =
5) How fast are you going?
6) How fast is a car moving?
7) When you're riding in a car, how fast are you moving?
8) If you kicked a ball into the air, and there was no gravity and no air resistance, what
would happen to the ball?
a) It would curve.
b) It would slow down.
c) It would keep going at a constant velocity.
d) It would keep going in a straight line.
e) It would keep going at the same speed.
9) If a basketball player shot the ball, but there was no gravity or air resistance, what would
happen to the ball after it left the player's hand?
10) When you're in a car and the car turns a corner, you tend to tip to the side. This is due to
a) your inertia.
b) the car's speed.
c) the car's mass.
d) all of the above
e) none of the above.
11) When you're in a car and the car starts up from a red light, you feel like you're pressed
back into your seat. What property does this illustrate?
12) Aristotle observed that all objects tend to come to a stop eventually, so he theorized that
they did so because it was their nature to stop moving. He knew they needed a force to
start moving. What force was Aristotle missing that Galileo found, allowing Galileo to
come up with the concept of inertia?
13) Aristotle believed in natural motion, that objects move to their natural state and stay there
unless moved by a force. Rocks, for example, fall down because they are earth. What
concept was Aristotle missing that Galileo found, allowing Galileo to come up with the
concept of inertia?
a) force
b) velocity
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c) friction
d) mass
e) acceleration
14) Why is it the "natural motion" for objects to stop moving?
15) If an object is changing speed, what do you know about the forces on it?
16) When a 50 kg person stands on a bathroom scale, what is the net force on the scale?
17) If a 1,000 kg car goes 100 m straight down the road in 10 s while traveling at a constant
10 m/s, what is the net force on it?
18) If you pull a 50 kg box with 200 N of force, and it doesn't move, what is the force of
friction on the box?
19) If you pull on a 10 kg box with 1 N of force, and the box doesn't move, how much
friction is on the box?
a) 0.1 N
b) 1 N
c) 9.8 N
d) 10 N
e) 98 N
20) Name something that operates without friction.
21) What kind of mechanical objects work with no friction?
22) A vector has
a) direction
b) force
c) magnitude
d) acceleration
e) magnitude and direction
23) What two features does a vector have?
24) Draw a picture of an airplane. It has a mass of 2,000 kg. It is flying at 400 kph. The air
resistance is 1,200 N, and the engines are putting out a force of 1,400 N. Draw and label
the vectors for velocity, air resistance, and engine force. Calculate the acceleration, then
draw and label the vector for acceleration.
25) Draw a picture of a car driving at 30 kph. The car has a mass of 1000 kg. The air
resistance is 500 N, the road friction is 600 N, and the driving force is 1500 N. Draw and
label the force vectors. Draw and label the velocity vector. Calculate, then draw and label
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the acceleration vector.
26) When is an object not in equilibrium?
a) When it is moving.
b) When the net force on it is not zero.
c) When ∑F = 0.
d) When it is moving at a constant velocity.
e) When it is not moving.
27) Can a moving object be in equilibrium? If so, how does that happen?
28) If an object moves in a curved path, there is not
a) a net force of zero.
b) an acceleration.
c) a force on it.
d) a change in velocity.
e) all of the above.
29) If a car goes around a corner at a constant speed, is it accelerating?
30) A bicyclist is riding at a constant velocity of 6 m/s. The force of road resistance is 12 N,
and air resistance is 18 N. What force is the bicyclist producing?
a) 6 N
b) 12 N
c) 30 N
d) 600 N
e) 630 N
31) If the force of road resistance is 25 N, and air resistance is 24 N, what force must a
bicyclist produce to maintain a constant speed of 7 m/s?
32) If you apply a net force of 10 N to a 10 kg rock, how fast will it accelerate?
a) 9.8 m/s2
b) 1 N
c) 1 m/s
d) 1 m/s2
e) not enough information
33) If you apply a net force of 20 N to a 4 kg rock, what will its acceleration be?
34) If you double the force on an object and cut the mass in half, its acceleration will
a) be 1/4 as much
b) be 1/2 as much
c) stay the same
d) be 2 times as much
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e) be 4 times as much
35) If you double the force on an object and double its mass too, what will happen to its
acceleration?
36) If you apply a net force of 100 N to a 10 kg rock, how fast will it accelerate?
a) 0.1 m/s2
b) 1 m/s2
c) 10 m/s2
d) 100 m/s2
e) 1,000 m/s2
37) Two people push on a car in the same direction. One pushes with 200 N of force, and the
other pushes with 300 N. The car has a mass of 1,500 kg. Neglecting friction, how fast
will the car accelerate?
38) What net force is required to accelerate a 1,000 kg car at 20 m/s2?
a) 0.02 N
b) 50 N
c) 980 N
d) 20,000 N
e) 40,000 N
39) What net force is required to accelerate a 1,000 kg car at 5 m/s2?
40) If you apply a 200 N net force to an object and it accelerates at 4 m/s2, what is its mass?
a) 20 g
b) 20 kg
c) 50 g
d) 50 kg
e) 800 kg
41) If you apply a 490 N net force to an object and it accelerates at 10 m/s2, what is its mass?
42) If your car has a mass of 2,000 kg, and you want it to go 1 km in 5 s, starting from rest,
how much force must it put out? (Ignore friction and air resistance.)
a) 10,000 N
b) 80,000 N
c) 100,000 N
d) 160,000 N
e) 200,000 N
43) If your car has a mass of 1,500 kg, and you want it to go 1 km in 10 s, starting from rest,
how much force must it put out? (Ignore friction and air resistance.)
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44) If your weight on Earth is 900 N, what is your approximate mass?
45) If your mass is 59 kg, what is your approximate weight on Earth (expressed in N)?
46) If you increase the net force on an object and you also increase its mass, what will happen
to its acceleration?
a) the acceleration will decrease
b) the acceleration will stay the same
c) the acceleration will increase
d) the acceleration will double
e) not enough information to tell
47) If you drop two objects of different masses, which will accelerate faster (ignore air
resistance)?
48) A parachutist jumps out of a plane. The mass of the parachutist and all her equipment is
100 kg. As she falls, she gains speed. At one instant, before reaching terminal velocity,
her instantaneous net acceleration is 5 m/s2. What is the force of air resistance on her at
that instant?
49) Describe mass, weight, and the differences between them.
50) An object can not exert a force on
a) another object
b) something that accelerates
c) something that doesn't move
d) nothing
e) something that moves at a constant speed
51) What is the minimum number of objects in order for a force to exist?
52) If you push on a car and it starts to move
a) you are pushing harder on it than it is on you.
b) it is pushing harder on you than you are on it.
c) the car is pushing on you equally as hard as you are pushing on it.
d) it is impossible to tell which is pushing harder.
e) the net force on the car equals zero.
53) If you throw a baseball, do you apply more force to the baseball, or does the baseball
apply more force to you?
54) What two properties of matter are directly proportional to mass?
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55) The force of gravity between Earth and the sun is about 41022 N. If Earth was twice as
far from the sun, about what would the force of gravity between them be?
56) If your weight on Earth is 800 N, and if you went up in a rocket so that you were orbiting
6,371 km above the surface of Earth, what would the force of Earth's gravity on you be?
57) Briefly state all three of Newton's Laws of Motion.
58) What is the most accurate definition of force?
a) push or pull
b) gravity
c) stress
d) ma
e) friction
59) In physics, what is the definition of force?
60) If you dropped a ball on Mercury, how fast would it be traveling after falling 5 m?
61) What is the weight of a 1,000 kg cow on Earth?
62) If you triple the mass of an object, what happens to its gravity?
63) If Earth had three times its mass, but was the same size, and you had twice the mass you
do now, by what factor would your weight change? Explain.
64) Earth has a radius of 6,371 km. How many meters up from the surface of Earth would
you have to go to weigh 1/4 as much as you do now?
65) Two steel balls are near each other. If everything else stayed the same,
but you made the little one twice as big, the other three times as big,
and you placed them three times as far apart, by what factor would the
gravitational force between them change?
66) Explain why objects all fall at the same rate, neglecting air resistance.
67) What is the minimum number of objects in order for a force to exist? Explain.
68) Identify at least 4 action-reaction pairs in the picture.
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69) As you sit in your chair, name two equal and opposite forces which are not an actionreaction pair.
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Dynamics Test Bank
#
1.
2.
3.
4.
5.
6.
7.
8.
9.
Answer
Concept
3 variables
3 variables
proportions
2
t = 2d/a
2 = at2/d
x kg = w lbkg/2.2 lb, or
x kg = w kg / 2.2
x mi = p km5/8
Relative to what?
Relative to what?
proportions
motion is relative
motion is relative
10.
c
It would continue at the same speed in a straight
line.
a
11.
inertia
12.
13.
14.
15.
16.
17.
18.
friction
c
Because of friction
The sum of forces is not zero.
Zero. The scale is in equilibrium.
Zero. It is traveling at a constant velocity.
200 N
19.
b
20.
There isn't anything that operates without friction.
21.
There isn't anything that operates without friction.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
e
magnitude and direction
The acceleration is 0.1 m/s2
The acceleration is 0.4 m/s2
b
Yes, when Fnet = 0. Or ∑F = 0.
a
Yes
c
49 N
d
5 m/s2
e
The acceleration won't change.
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inertia - no outside forces
inertia - no outside forces
inertia, acceleration,
friction
inertia, acceleration,
friction
friction
friction
friction
acceleration
equilibrium
equilibrium
friction, static equilibrium,
∑F=0
friction, static equilibrium,
∑F=0
friction - you can't get away
from it
friction - you can't get
away from it
vectors
vectors
vectors, a=F/m
vectors, a=F/m
equilibrium, ∑F=0
equilibrium, ∑F=0
acceleration and force
acceleration and force
dynamic equilibrium, ∑F=0
dynamic equilibrium, ∑F=0
a=F/m
a=F/m
a=F/m, aF, a1/m
a=F/m, aF, a1/m
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36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
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Answer
Concept
c
0.33 m/s2
d
5,000 N
c
49 kg
d
30,000 N
90 kg, or 91.8 kg
590 N
e
They will accelerate the same.
500 N
Mass is always the same - the amount of stuff.
Weight is a force. It is the product of mass and
acceleration, ma (mg on Earth). Weight changes
depending on the gravity.
d
two
c
Neither. The forces are equal and opposite.
Inertia and gravity
11022 N
200 N
 1st - inertia. Objects will have a constant
velocity unless a force acts on them.
 2nd - Fnet=ma. a  F, a  1/m.
 3rd - action-reaction. If an object exerts a force
on another object, the 2nd object exerts an equal
and opposite force on the 1st.
d
force = mass  acceleration
a=F/m
a=F/m
action-reaction
F=ma
action-reaction
m=F/a
F=ma
a=2d/t2, F=ma
weight, wt=F/g
weight, wt=F/g
a=F/m
a=F/m
F = ma
mass and weight
10,000 N
It triples.
6. Earth would pull three times as hard, and I would
pull twice as hard. F = Gmm/d2
6371 m
2/3
Because F is proportional to m. If you double the
mass, the inertia (resistance to acceleration)
doubles, but the force that causes acceleration
doubles, too.
F = ma
F = Gmm/d2
F  mm
9
m=F/a
action-reaction
action-reaction
action-reaction
mass
g1/d2
g1/d2
Newton's Laws of Motion
a=2d/t2, F=ma
force
F  1/d2
F = Gmm/d2
a = F/m
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67.
68.
69.
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Answer
Two. Newton’s 3 Law. An object can’t exert a
force on nothing
Hammer-hands, hands-hammer; feet-floor, floorfeet; computer-table, table-computer; table-floor,
floor-table; glasses-nose, nose-glasses;
Earth-me, chair-me
rd
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Concept
action-reaction
action-reaction
action-reaction