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Conceptual Physics: Form TR2.15A
Name ______________________________
TEST 2 REVIEW
Date _________________ Period _____
Test Review # 2
Speed. Speed is the change in distance per unit of time. It is often used interchangeably with velocity, although they are not the same.
Velocity has a direction. Speed is the magnitude or size of a velocity. The symbol“v” is often used even in formulas where direction is not
important. If “d” is the symbol for distance, and “t” is the symbol for time, the calculational formula can be written:
v=
d
t
d = vt
t=
d
v
Sample Problem
How long does it take to travel 9,750 km at a speed of 75 km/h?
t=
d 9,750km
=
= 130h
v
75 km
h
Acceleration. Whether you are speeding up, slowing down, or just changing direction, any change in velocity is acceleration. When
an object falls from a window, it is accelerating. When a plane lands and comes to a stop, it is accelerating. As the earth zips around
the sun it is accelerating. A car that goes from zero to 50 km/h in 5 seconds is accelerating. A car that goes from zero to 100 km/h
in 5 seconds is also accelerating. The accelerations are not equal, however. A car that goes from zero to 100 km/h in 5 seconds has
a greater acceleration than one that goes from zero to 50 km/h in 5 seconds. Acceleration is the change in velocity over time.
Acceleration, time, and the final velocity can be calculated as shown below.
a=
v f − vi
∆v v f − vi
=
;t=
;
t
t
a
and v f = vi + at
• a = acceleration
• ∆v = change in velocity
v f = final velocity
vi = initial velocity
Sample Problem 1
What is the acceleration of a car that
speeds up from 85 km/h to 100 km/h in 3
seconds?
a=
a=
v f − vi
t
100 km h − 85 km h
3s
= 5 km h ⋅ s
Sample Problem 2
A falling brick passes a window at a speed
of 29.4 m/s. How fast will it be going 2
seconds later if the acceleration of gravity
is 9.8 m/s2?
v f = vi + at
(
v f = 29.4 m + 9.8 m
s
= 49.0 m
s
s2
)(2s)
Sample Problem 3
How long does it take to stop a car going
88 km/h if it accelerates at a rate of
–5 km/h/s?
t=
v f − vi
a
km
− 88 km
0
h
h
t=
km
−5
h⋅s
= 17.6s
Conceptual Physics: Form TR2.15A
Test Review 2
TEST 2 REVIEW
Page 2
Free Fall. A pot falls from a window. Before it fell, its speed was 0 m/s. As it fell, it sped up or accelerated. The speed increased the entire
time it was falling. Since the initial speed was 0 m/s, the final speed can be expressed as : vf = at. The final speed of an object with a
constant acceleration after a given amount of time has passed is also called the instantaneous speed. The acceleration of gravity, g, is 9.8
m/s2. For an object in free fall with an initial speed of 0 m/s, the final speed is: vf = gt. If the initial speed of the falling object, vi , is not
zero, it needs to be added to get the instantaneous or final speed: vf = gt + vi.
Sample Problem 1
A child drops a toy out of a window. It falls for 3.0 seconds.
How fast is it going just before it hits?
Step 1: Write the values of the variables
vi = 0 m/s
t=3s
g = 9.8 m/s2
Step 2: Substitute values into the equation
vf = gt + vi
Sample Problem 2
A child bounces a ball by throwing it down at 3.0 m/s. It hits
the ground after 0.25 seconds. How fast is it going just
before it hits?
Step 1: Write the values of the variables
vi = 3.0 m/s
t = 0.25 s
g = 9.8 m/s2
Step 2: Substitute values into the equation
vf = gt + vi
vf = (9.8 m/s2)(3 s) + 0 m/s = 29.4 m/s
vf = (9.8 m/s2)(0.25 s) + 3.0 m/s = 5.45 m/s
In Sample Problem 1, we calculated that an object that falls for 3.0 seconds with an
initial speed of 0 m/s reaches a speed of 29.4 m/s. Since the acceleration is constant,
the average speed between any two measurements is the midpoint. It is found by
adding the two values and dividing by two. The average speed of the falling object
was:
v +v
29.4 m + 0 m
v average =
1
f
2
=
s
2
s
= 14.7 m s
A penny falling from the Empire State Building hits
the ground in 9.5 seconds. How far did it fall?
Step 1: Write the values of the variables
vi = 0 m/s
t = 9.5 s
a = g = 9.8 m/s²
Step 2: Substitute values into the equation
In the three seconds it was falling, it traveled a distance d = vt = (14.7 m/s)(3.0 s) =
d = ½at 2 + vit
44.1 m. The same result can be obtained using the formula d = ½at 2 + vit
d = ½(9.8 m/s2)(9.5 s)2 + (0 m/s)(9.5 s) = 442 m
d = ½at 2 + vit = ½(9.8 m/s²)(3.0 s)2 = 44.1 m
Forces. A force is a push or a pull. Forces are measured in Newtons (N) in the
metric system. More than one force can act on an object at a time. The net force is
the combination of all the forces acting on an object. For forces acting in the same direction, the net force is the sum of the forces. For
forces acting in opposite directions the net force is the difference between of the forces. If the forces are equal and opposite, the net force
is zero. Forces acting at right angles form a net or resultant force that is the hypotenuse of a right triangle with the two forces as the sides.
The size of the force can be determined by the Pythagorean theorem (a2 + b2 = c2).
Sample Problems:
Problem 1
What is the resultant force on an object when it is acted on by three
forces; 2 N east, 5 N west, and 4 N east.
Step 1: Add the forces that are acting in the same direction.
2 N east + 4 N east = 6 N east
Step 2: Subtract the forces that are in the opposite direction. (NOTE:
The net force is in the direction of the larger force.)
6 N east – 5 N west = 1 N east
Problem 2
What is the net force on an object when it is acted on by a force of
1.5 N east and 2 N south.
Step 1: Apply the Pythagorean theorem
c2 = (1.5)2 + (2)2 =2.25 + 4 = 6.25
Step 2: Find the square root
c = c 2 = 6.25 = 2.5 N southeast
Newton’s First Law of Motion. According to Newton’s First Law of Motion, if the net force on an object is zero, it maintains its state
of motion. This means an object in motion will remain in motion at the same speed and in the same direction, while an object at rest will
remain at rest. People did not always realize this. Since moving objects eventually come to a stop, people thought the natural state for an
object was to be at rest. In order to be in motion, people thought an object had to have a force applied to it. This is because they did not
know about friction. A force only needs to be applied to keep a moving object in motion in order to overcome friction. Friction is a force
that acts to resist sliding between touching surfaces. There are three main types: Static friction – the force that prevents an object at rest
from moving when a force is applied; Sliding friction – the force that resists the movement of one surface past another (usually less than
static friction); and Rolling friction – friction that results when an object rolls across a surface (usually less than sliding friction). Friction
is caused by molecular adhesion, surface roughness, and the plowing effect. Molecular adhesion is a force of attraction between molecules
Conceptual Physics: Form TR2.15A
Test Review 2
TEST 2 REVIEW
Page 3
resulting when two materials are brought into close contact with each other. Greater surface roughness increases friction, especially when
the materials are rough enough to cause serious abrasion. The plowing effect results when one or more of the materials is relatively soft,
and becomes deformed, getting in the way of movement.
Newton’s Second Law of Motion. Newton’s first law of motion says an object’s state of motion will not change unless an unbalanced
force is applied to it. This implies that if an unbalanced force is applied to an object, its state of motion will change. Any change in motion
is acceleration. So, force causes acceleration. Now imagine, the same force is used to toss a softball into the air and to toss a bowling ball
into the air. Which one will accelerate more? The one with the smaller mass accelerates more. This is essentially Newton’s Second Law.
Newton’s Second Law of Motion says the acceleration of an object is equal to the net force divided by the mass.
acceleration =
net force
mass
Any of the three variables, force (Fnet), mass (m), or acceleration (a), can be determined if the other two variables are
known. Since the acceleration due to gravity is a constant 9.8 m/s2, the weight of an object, which is the downward force
of gravity on the object, can be calculated using the same formula if the mass is known. The units of force are newtons (N),
where 1 N = 1 kg•m/s2.
Sample Problem 1
What is the acceleration of a 15 kg object
that is pushed with a net force of 300. N?
F 300 N 300. kg •m s2
a= =
=
= 20. m s2
m 15kg
15kg
Sample Problem 2
What is the weight of a 65 kg object?
F = ma = (65kg )(9.8 m s2 ) =
637
kg • m
s2
= 637 N
Sample Problem 3
What is the mass of an object that weighs
441 N?
m=
F 425 N 441 kg•m s2
=
=
= 45kg
a 9.8 m s2
9.8 m s2
Changing Motion and Turning. According to Newton's First Law, an object in motion continues moving in a straight line unless it is
acted on by a force. Planets orbit the sun in an almost circular path. They are not violating Newton's First Law. They are obeying Newton's
Second Law. The sun is exerting a force on the planets that keeps them revolving.
Force and acceleration are directional. A net force opposite an object's motion is negative and produces a negative acceleration, slowing
the object down. A net force in the same direction as an object's motion is positive and produces a positive acceleration, speeding the object
up. A net force at an angle to an object's motion will cause the object to change direction. If a force is maintained on an object at an angle
to it's motion, it will cause it to follow a curved path or turn. When an unbalanced force is applied to an object at right angles to the object's
motion the object travels in a circle. Such a force is called a centripetal force. A centripetal force is toward the center of the object's circular
path. This is what keeps planets moving around the sun.
Air Resistance. Air resistance can benefit us, or it can get in the way. Either way, it is a fact of life. When an object passes through air,
the air particles need to move out of the way for the object to pass. Air pushing against the moving object produces resistance or drag.
Normally, the effect of air resistance is so small that we don’t notice it. The faster the object moves, however, the greater the resistance
is. Stick your hand out the window of a moving car, and you’ll feel the resistance. This resistance costs motorists time and money. An object
falling through the air speeds up because of gravity. This increases the air resistance. When the air resistance equals the gravitational pull,
the net force is zero, and the object stops accelerating. Then the object falls at a constant speed called terminal velocity. The acceleration
due to gravity is the same for all objects, but air resistance is not. A falling leaf floats slowly through the air. This is because its large surface
interacts with a large number of air molecules. Parachute jumpers depend on this to land safely.
If the force of the air resistance on a falling object is known, the affect on its acceleration can be determined.
Sample Problem
What is the acceleration of a 2.0 kg object falling through air if the air resistance is 3.0 N?
Step 1: Determine the weight of the object
F = ma = (2.0kg )( 9.8 m s2 ) = 19.6 N
Step 2: Determine the net force on the object
Fnet = Fweight − Fair resistance = 19.6 N − 3.0 N = 16.6 N
Step 3: Determine the acceleration
F
16.6 N
a = net =
= 8.3 m s2
m
2.0kg
Conceptual Physics: Form TR2.15A
Test Review 2
TEST 2 REVIEW
Page 4
Center of Mass. Objects don’t have their mass distributed evenly. Archimedes, an ancient Greek mathematician, showed that the effect
on rigid bar by weights resting at various points along it is the same as it would be if all the weights were moved to a single point. This point
is called the center of mass or the center of gravity. If you try to balance an object, it will only balance over its center of mass. If the
center of mass is not over the base, the object will fall. The center of mass of a system of particles is a specific point at which the system’s
mass behaves as if it were concentrated. In the case of a rigid body, its position is fixed in relation to the object (but not necessarily in
contact with it). The geometric center of an object is not necessarily its center of mass. It is easiest to interpret the way an object responds
to forces by looking at the behavior of the center of mass. This makes it a very significant point to engineers. Engineers try to design a
sports car so its center of gravity is as low as possible to make the car handle better. For a plane to be safe to fly, the center of gravity
should be about one quarter of the way from the wing leading edge to the wing trailing edge.
Newton’s Third Law. According to Newton’s Third Law, forces always act in equal but opposite pairs. For every action force, there is
an equal but opposite reaction force. When you push on a wall, the wall pushes back on you. The action force and the reaction force are
on two different objects. As a result, action and reaction forces don’t cancel each other..
Action-reaction forces are a bit confusing when it comes to gravity. Gravity pulls down on you, but gravity is a mutual force of
attraction. You are also pulling up on the earth. These forces make up one unbalanced action-reaction force pair. When you stand on a
surface, your weight presses down, and the surface presses up. This makes up another unbalanced action-reaction force pair. Out of these
four forces, there are some balanced forces. Gravity and the surface you are standing on are both exerting forces that are acting on you.
These forces are balanced. As a result, you are not moving. But if you press down with a force greater than your weight, the reaction force
is enough to overcome gravity. This is what happens when you jump.
Jet Propulsion. If you blow up a balloon and let it go without tying it, the balloon flies away. The shrinking balloon forces air out the
opening. But when the balloon pushes on the air, the air pushes back causing the balloon to move. A jet and a rocket ship move in much
the same way. When the fuel in a jet engine or a rocket ship burns, hot gases are released that expand and press against the walls of the
chamber. According to Newton’s Third Law, the chamber pushes back against the fuel. If there is an opening at one end of the chamber,
the expanding gases move out. In order for the molecules to move out of the chamber there must be a net (unbalanced) force. In response,
there is a net reaction force at the other end of the chamber. This causes the jet or the rocket ship to move in the opposite direction of the
escaping, hot gas molecules.
Weightlessness. When you step on a scale, gravity presses you down on the scale with a force equal to your weight. According to Newton's
third law, the scale presses back. Suppose the floor beneath the scale suddenly gives way and you are falling together with the scale. Gravity
is moving you and the scale together. The scale is not pushing up on you. According to Newton's third law, you are not pushing down on
the scale. The scale measures your weight to be zero. You feel weightless because nothing is pushing up on you. Weightlessness in orbit
is pretty much the same phenomenon. An object in orbit is falling towards the earth, but it is also moving away from the earth (at a right
angle). All the objects in a space craft in orbit are also falling. As a result, they feel weightless. Keep in mind, however, that weight is the
downward force due to gravity. Anything that is orbiting the earth is being pulled down by gravity, or it would take off into space instead
of orbiting. As a result, technically, it still has weight regardless of how it feels.
Answer the questions below by circling the number of the correct response
1. How fast are you traveling if a 4,500 km trip takes 4.5 h?
(1) 1,000 km/h (2) 20,250 km/h (3) 0.001 km/h (4) 4504.5 km/h
7. What measures the quantity of matter? (1) speed (2) weight
(3) acceleration (4) mass
2. How far can you go in 3.0 h at 85 km/h? (1) 0.035 km (2) 28.33 km
(3) 255 km (4) 88 km
8. Which of the following objects is NOT accelerating? (1) a jogger
moving at a constant speed (2) a car that is slowing down (3) Earth
orbiting the Sun (4) a car that is speeding up
3. How long will it take to run a 0.4 km track at a speed of 0.16 km/min?
(1) 0.56 min (2) 0.064 min (3) 0.4 min (4) 2.5 min
4. How fast will a runner be going if she speeds up from 2.7 m/s by
accelerating at a rate of 0.5 m/s2 for 6 s? (1) 3.0 m/s (2) 5.7 m/s
(3) 0.3 m/s (4) 16.2 m/s
5. How long does it take for a car going 40 km/h to speed up to 75 km/h
with an acceleration of 10 km/h/s? (1) 3.5 s (2) 350 s (3) 7.5 s
(4) 4 s
6. What is the acceleration of a car that goes from a stop to 88 km/h in
4.0 s? (1) 352 km/h/s (2) 22 km/h/s (3) 0.045 km/h/s
(4) 92 km/h/s
9. Which of the following equals speed? (1) acceleration/time
(2) (change in velocity)/time
(3)
distance/time
(4) displacement/time
10. Which of these is an acceleration? (1) 5 m east (2) 15m/s east
(3) 52 m/s2 east (4) 32 s2 east
11. Resistance to a change in motion increases when which of these
increases? (1) velocity (2) speed (3) instantaneous speed (4) mass
12. What is 18 cm/h north an example of? (1) speed (2) velocity
(3) acceleration (4) momentum
Conceptual Physics: Form TR2.15A
Test Review 2
TEST 2 REVIEW
13. Which is true when the velocity and the acceleration of an object are
in the same direction? (1) The object's speed is constant. (2) The
object changes direction. (3) The object speeds up. (4) The object
slows down.
Page 5
Use the figure below to answer questions 23 - 25.
Speed v. Time
14. Which of the following equals the change in velocity divided by the
time? (1) speed (2) displacement (3) momentum (4) acceleration
15. You travel to a city 200 km away in 2.5 hours. What is your average
speed in km/h? (1) 180 km/h (2) 12.5 km/h (3) 80 km/h (4) 500
km/h
16. From the graph below, which object is moving the fastest?
23. What is the acceleration between 0 and 2 s? (1) 10 m/s2 (2) 5 m/s2
(3) 0 m/s2 (4) –5 m/s2
(1) A (2) B (3) C (4) It isn’t possible to tell
17. What is the distance traveled divided by the time taken to travel that
distance? (1) acceleration (2) velocity (3) speed (4) inertia
18. Sound travels at a speed of 330 m/s. How long does it take for the
sound of thunder to travel 1,485 m? (1) 45 s (2) 4.5 s (3) 4,900 s
(4) 0.22 s
24. During what time period does the object have a constant speed? (1)
between 1 and 2 s (2) between 2 and 3 s (3) between 4 and 5 s (4)
between 5 and 6 s
25. What is the acceleration between 4 and 6 s? (1) 10 m/s2 (2) 4 m/s2
(3) 6 m/s2 (4) –3 m/s2
26. An acorn falls from the top of an oak and accelerates at 9.8 m/s2. It
hits the ground in 1.5 s. What is the speed of the acorn when it hits
the ground? (1) 9.8 m/s (2) 15 m/s (2) 20 m/s (4) 30 m/s
Use the figure below to answer questions 19 and 20.
27. A sports car and a moving van are traveling at a speed of 30 km/h.
Which vehicle will be easier to stop and why? (1) the moving van,
because it has more mass (2) the moving van, because it has
greater acceleration (3) the sports car , because it has less mass
(4) the sports car , because it has lower acceleration
19. During which time period is the ball's average speed the fastest?
(1) between 0 and 1 s (2) between 1 and 2 s (3) between 2 and 3
s (4) between 3 and 4 s
20. What is the average speed of the ball? (1) 0.75 m/s (2) 1 m/s
(3) 10 m/s (4) 1.3 m/s
21. A car accelerates from 15 m/s to 30 m/s in 3.0 s. What is the car's
acceleration? (1) 10 m/s2 (2) 25 m/s2 (3) 15 m/s2 (4) 5.0 m/s2
22. Which of the following can occur when an object is accelerating?
(1) It speeds up. (2) It changes direction. (3) It slows down. (4) all
of the above
28. A girl walks 2 km north, then 2 km east, then 2 km south, then 2 km
west. What is her displacement? (1) 0 km (2) 2 km (3) 3 km
(4) 8 km
29. A girl leaves school at 3:00 and starts walking home. Her house is 2
km from school. She gets home at 3:30. What was her average
speed? (1) 1 km/h (2) 2 km/h (3) 3 km/h (4) 4 km/h
30. A football, a hockey puck, and a tennis ball all fall down in the
absence of air resistance. Which of the following is true about their
acceleration? (1) The acceleration of the football is greater than the
other two.(2) The acceleration of the hockey puck is greater than the
other two. (3) The acceleration of the tennis ball is greater than the
other two. (4)They all fall down with the same constant acceleration.
(5) More information is required .
Conceptual Physics: Form TR2.15A
Test Review 2
TEST 2 REVIEW
Page 6
31. A tennis ball is dropped from the top of a tall building. A second
tennis ball is thrown down from the same building. Make a statement
about the acceleration of each tennis ball. (1) The first ball falls with
a greater acceleration. (2) The second ball falls with a greater
acceleration. (3) They both fall with the same acceleration because
they started from the same height. (4) The both fall with the same
acceleration because they are in a free fall. (5) More information is
required
45. What is the acceleration of an 81 kg object that is pushed with a net
force of 243 N? (1) 0.33 m/s2 (2) 324 m/s2 (3) 3 m/s2 (4) 162 m/s2
46. What is the mass of an object that weighs 196 N? (1) 0.05 kg
(2) 20 kg (3) 1,921 kg (4) 196 kg.
32. How far will a brick starting from rest fall freely in 3.0 seconds?
(1) 15 m (2) 29 m (3) 44 m (4) 88 m
48. What is the acceleration of a 15 kg object falling through air if the air
resistance is 42 N? (1) 7 m/s2 (2) 57 m/s2 (3) 27 m/s2 (4) 9.4 m/s2
33. How far will a pot fall from a window in 2.5 seconds? (1) 31 m
(2) 12 m (3) 25 m (4) 61 m
49.
Which of the following changes when an unbalanced force acts on
an object? (1) mass (2) motion (3) inertia (4) weight
Answer questions 34-36 about a ball that falls from the roof of a tall
building:
50.
Which of the following is the force that slows a book sliding on a
table? (1) gravity (2) static friction (3) sliding friction (4) inertia
34. How fast will it be going after 10 seconds?
51.
Two students are pushing on the left side of a box and one student
is pushing on the right. The diagram below shows the forces they
exert. Which way will the box move?
47. What is the weight of a 27 kg mass? (1) 0.36 N (2) 265 N (3) 2.8
N (4) 27 N
35. What is the average speed while falling
36. How far did it fall?
37. A body builder bench presses a 980 N barbell with an upward force
of 1050 N. What is the net force on the barbell? (1) 70 N up (2) 70
N down (3) 2030 N up (4) 2030 N down
38. Two football players grab hold of a football. One pulls the ball north
with a force of 600 N. The other pulls the ball east with a force of 800
N. What is the net force on the football? (1) 1400 N east (2) 200 N
north (3) 1,000 N northeast (4) 480,000 N northeast
39. Two workers push on a crate, one with a force of 550 N east, and the
other with a force of 720 N east. The crate is held in place by a
spring that pulls west with a force of 930 N. What is the net force on
the crate? (1) 2,150 N west (2) 340 N east (3) 1,100 N west
(4) 760 N east
40. What is the net force on an object that is traveling in a straight line
at a constant speed of 50 m/s? (1) 0 N (2) 50 N (3) 5 N (4) 500 N
41. A force of 30 N east is needed to slide a box at a constant speed.
What is the force of friction on the box? (1) 0 N (2) 30 N east
(3) 30 N west (4) There is not enough information to tell.
(1) up (2) left (3) down (4) right
52.
What combination of units is equivalent to the newton? (1) m/s2
(2) kg-m/s (3) kg-m/s2 (4) kg/m
53.
Which of the following is a push or a pull?
(2) momentum (3) acceleration (4) inertia
54.
An object is accelerated by a net force in which direction? (1) at an
angle to the force (2) in the direction of the force (3) in the
direction opposite to the force (4) Any of these is possible.
55.
You are riding on a bike. In which of the following situations are the
forces acting on the bike balanced? (1) You pedal to speed up.
(2) You turn at constant speed. (3) You coast to slow down.
(4) You pedal at constant speed.
56.
Which of the following has no direction? (1) force (2) acceleration
(3) weight (4) mass
2
42. What is the mass of an object that accelerates at 20.0 m/s as a
result of a 15 N force? (1) 1.33 kg (2) 35 kg (3) 0.75 kg (4) 5 kg
43. What is the acceleration of a 45 kg object that is pushed with a net
force of 630. N? (1) 14 m/s2 (2) 7.14 m/s2 (3) 28,350 m/s2 (4) 675
m/s2
44. What is the net force required to accelerate a 24 kg object at 18
m/s2? (1) 1.33 N (2) 0.75 N (3) 42 N (4) 432 N
(1) force
Conceptual Physics: Form TR2.15A
Test Review 2
TEST 2 REVIEW
Page 7
67.
An object acted on by a force of 2.8 N has an acceleration of 3.6
m/s2. What is the mass of the object? (1) 0.78 kg (2) 1.29 kg (3)
10.1 kg (4) 6.4 kg
57.
Why does the speed of a sled increase as it moves down a snowcovered hill, even though no one is pushing on the sled. (1) due
to friction (2) due to inertia (2) due to momentum (4) due to
gravity
58.
Two balls of the same size and shape are dropped from a
helicopter. One ball has twice the mass of the other ball. On which
ball will the force of air resistance be greater when terminal velocity
is reached? (1) the heavier one (2) the lighter on (3) they will
both be the same.
Object
What is the net force on the box pictured below?
Book
Use the table below to answer questions 68 and 69.
59.
Mass of Common Objects
Cup
61.
What is the weight of a book that has a mass of 0.35 kg? (1) 0.036
N (2) 3.4 N (3) 28 N (4) 34 N
62.
If you swing an object on the end of a string around in a circle, the
string pulls on the object to keep it moving in a circle. What is the
name of this force? (1) inertial (2) centripetal (3) resistance
(4) gravitational
63.
What is the acceleration of a 1.4-kg object if the gravitational force
pulls downward on it, but air resistance pushes upward on it with a
force of 2.5 N? (1) 11.6 m/s2, downward (2) 11.6 m/s2, upward
(3) 8.0 m/s2, downward (4) 8.0 m/s2, upward
64.
65.
66.
1,100
240
Ruler
25
620
68.
Which object would have an acceleration of 0.89 m/s2 if you pushed
on it with a force of 0.55 N? (1) book (2) can (3) ruler (4) stapler
69.
Which object would have the greatest acceleration if you pushed on
it with a force of 8.2 N? (1) can (2) stapler (3) ruler (4) book
.
(1) 3 N up (2) 7 N left (3) 3 N left (4) 6 N down
Which of the following descriptions of gravitational force is not true?
(1) It depends on the mass of objects. (2) It is a repulsive force.
(3) It depends on the distance between objects. (4) It exists
between all objects.
380
Can
Stapler
60.
Mass (g)
Use the figure below to answer questions 70 and 71.
70.
The figure above shows the horizontal forces that act on a box that
is pushed from the left with a force of 12 N. What force is resisting
the horizontal motion in this illustration? (1) friction (2) gravity
(3)inertia (4) momentum
71.
A skater is coasting along the ice without exerting any apparent
force. Which law of motion explains the skater's ability to continue
moving? (1) Newton’s First Law (2) Newton’s Second Law
(3) Newton’s Third Law (4) Newton’s Fourth Law
What is the acceleration of the box? (1) 27 m/s2 (2) 4.8 m/s2
(3) 4.3 m/s2 (4) 0.48 m/s2
72.
After a soccer ball is kicked into the air, what force or forces are
acting on it? (1) the kick only (2) weight only (3) air resistance
only (4) weight and air resistance
What is the acceleration a 1.4-kg object falling through the air if the
force of air resistance on the object is 2.5 N? (1) 3.9 m/s2 (2) 8.0
m/s2 (3) 9.2 m/s2 (4) 1.1 m/s2
73.
Two 20.-newton forces act concurrently on an object. What angle
between these forces will produce a resultant force with the
greatest magnitude? (1) 0° (2) 45° (3) 90.° (4) 180.°
What is the force on an 8.55-kg object that accelerates at 5.34
m/s2. (1) 0.62 N (2) 45.7 N (3) 1.60 N (4) 13.89 N
Conceptual Physics: Form TR2.15A
Test Review 2
TEST 2 REVIEW
78.
Why are sports cars more stable in quick turns than trucks?
(1) Sports cars have a lower center of mass. (2) Sports cars have
a higher center of mass. (3) Sports cars have no center of mass.
(4) Sports cars have a moveable center of mass.
79.
You push a box east with a force of 23 N. The box (1) pushes you
east with a force of 23 N, (2) pushes you west with a force of 23 N.
(3) moves east without pushing you in any direction. (4) pushes you
with an unknown force.
Which law of physics that explains how balloons, jets, and rocket
ships fly? (1) Newton’s first law, (2) Newton’s second law,
(3) Newton’s third law, (4) Newton’s fourth law.
80.
81.
A 600 N man contracts his leg muscles and presses down on the
ground with a force of 700 N. What happens as a result? (1) The
man jumps up with a net force of 100 N. (2) The ground moves
down with a net force of 100 N. (3) The man is pushed down with
a net force of 100 N. (4) The man jumps up with a net force of
1,300 N.
Answers
Bowling pins are hard to knock over because their center of mass
is (1) high, (2) low, (3) hard to locate, (4) small.
1
4
2
1
4
3
1
3
2
1
4
4
1
2
1
2
3
1
3
1
3
77.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.
A heavy box sits on a sidewalk. If you push against the box, the box
moves in the direction of the force. If the box is replaced with a ball
of the same mass, and you push with the same force against the
ball, how will the acceleration compare? (1) It will be larger. (2) It
will be smaller. (3) It will be the same.
A rock is thrown straight up into the air. At the highest point of the
rock's path, the magnitude of the net force acting on the rock is
(1) less than the magnitude of the rock's weight, but greater than
zero, (2) greater than the magnitude of the rock's weight, (3) the
same as the magnitude of the rock's weight, (4) zero.
1
4
3
2
2
1
2
3
2
3
1
2
4
4
4
1
3
2
2
2
3
76.
84.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
What effect would throwing the ball harder have? (1) The path
wouldn’t curve. (2) The acceleration of gravity would be larger.
(3) The acceleration of gravity would be smaller. (4) The ball would
go higher.
A car traveling west in a straight line on a highway decreases its
speed from 30.0 meters per second to 23.0 meters per second in
2.00 seconds. The car’s average acceleration during this time
interval is (1) 3.5 m/s2 east (2) 3.5 m/s2 west (3) 13 m/s2 east
(4) 13 m/s2 west
4
2
2
4
2
3
1
4
4
4
3
1
980 m/s
490 m/s
4900 m/s
1
3
2
1
3
3
75.
83.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
The figure above shows the path a ball thrown into the air follows.
What causes the ball to move along a curved path? (1) air
resistance (2) gravity acting opposite the direction to the ball’s
movement (3) gravity acting in the same direction as the ball’s
movement (4) gravity acting at an angle to the direction to the
ball’s movement
An astronaut in a satellite orbiting the earth feels weightless
because (1) the astronaut doesn’t weigh anything, (2) there is no
gravity in space, (3) the astronaut is falling at the same rate as the
satellite, (4) the satellite has no gravity.
1
3
4
2
1
2
4
1
3
3
4
2
3
4
3
3
3
2
1
1
4
74.
82.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Use the figure below to answer questions 74 and 75.
Page 8