Forces
Forces
Preview
• Understanding Concepts
• Reading Skills
• Interpreting Graphics
Standardized Test Prep
Forces
Standardized Test Prep
Understanding Concepts
1. After a bank customer cashes a check, some of the
money received accidentally slips from the customer’s
hands. What force causes the bills to hit the ground
later than the coins do?
A.
B.
C.
D.
static friction
gravity
air resistance
magnetism
Forces
Standardized Test Prep
Understanding Concepts
1. After a bank customer cashes a check, some of the
money received accidentally slips from the customer’s
hands. What force causes the bills to hit the ground
later than the coins do?
A.
B.
C.
D.
static friction
gravity
air resistance
magnetism
Forces
Standardized Test Prep
Understanding Concepts, continued
2. If the nickel and iron at the Earth’s core were suddenly
replaced with cotton candy, what would happen to the
mass and weight of the objects on the Earth’s surface?
F. Their mass and weight both increase.
G. Their mass would stay the same and their weight
would decrease.
H. Their mass would decrease and their weight would
increase.
I. Neither their mass nor weight change.
Forces
Standardized Test Prep
Understanding Concepts, continued
2. If the nickel and iron at the Earth’s core were suddenly
replaced with cotton candy, what would happen to the
mass and weight of the objects on the Earth’s surface?
F. Their mass and weight both increase.
G. Their mass would stay the same and their weight
would decrease.
H. Their mass would decrease and their weight would
increase.
I. Neither their mass nor weight change.
Forces
Standardized Test Prep
Understanding Concepts, continued
3. A truck with a mass of 2,000 kg is traveling at a
constant velocity of 40 m/s. What is the net force acting
upon the truck?
A.
B.
C.
D
0.0 N
0.02 N
50 N
800 N
Forces
Standardized Test Prep
Understanding Concepts, continued
3. A truck with a mass of 2,000 kg is traveling at a
constant velocity of 40 m/s. What is the net force acting
upon the truck?
A.
B.
C.
D
0.0 N
0.02 N
50 N
800 N
Forces
Standardized Test Prep
Understanding Concepts, continued
4. A high-altitude balloonist at an altitude of 15,000 m
drops an instrument package. When does the package
reach terminal velocity?
F.
G.
H.
I.
as it begins to fall
as it matches the speed of the plane
as it stops accelerating from air resistance
as it impacts the Earth’s surface
Forces
Standardized Test Prep
Understanding Concepts, continued
4. A high-altitude balloonist at an altitude of 15,000 m
drops an instrument package. When does the package
reach terminal velocity?
F.
G.
H.
I.
as it begins to fall
as it matches the speed of the plane
as it stops accelerating from air resistance
as it impacts the Earth’s surface
Forces
Standardized Test Prep
Understanding Concepts, continued
5. Explain why the moon does not fly off into space in a
straight line nor plummet directly toward the Earth’s
surface.
Forces
Standardized Test Prep
Understanding Concepts, continued
5. Explain why the moon does not fly off into space in a
straight line nor plummet directly toward the Earth’s
surface.
Answer: The forward and downward motions combine to
produce an orbit.
Forces
Standardized Test Prep
Understanding Concepts, continued
6. A racing motorcycle with a mass of 300 kg accelerates
from 0 to 60 m/s in 5 seconds. How much force is acting
on the motorcycle?
Forces
Standardized Test Prep
Understanding Concepts, continued
6. A racing motorcycle with a mass of 300 kg accelerates
from 0 to 60 m/s in 5 seconds. How much force is acting
on the motorcycle?
Answer: 3,600 N
Forces
Standardized Test Prep
Reading Skills
A REGULAR VISITOR
A microgravity environment is one in which the apparent weight
of an object is much less than its weight on Earth. The term
microgravity is used instead of weightlessness because every
object has some weight, though that weight may be so minuscule
as to be undetectable. Because every object in the universe exerts
a gravitational pull on every other object, every object possesses
weight.
Microgravity occurs whenever an object is in free fall. Scientists
achieve microgravity environments in a number of ways. Drop
towers and research aircraft provide it for up to 20 s. The Shuttle
and the International Space Station can provide it for months.
Forces
Standardized Test Prep
Reading Skills, continued
A REGULAR VISITOR, continued
A rocket ship that is accelerating by firing its rockets cannot
provide microgravity. Even if the rocket is accelerating uniformly,
force is applied to the rocket by the gas escaping out the back. This
force must be transferred to each part of the ship through either
pressure or tension, and thus weightlessness is not experienced.
Forces
Standardized Test Prep
Reading Skills, continued
7. When the Shuttle is orbiting, it is in constant motion
around the Earth. Why isn’t this motion experienced as
weight?
A. There is no net force acting on the Shuttle.
B. The Shuttle’s mass is not large enough to exert a
measurable gravitational pull.
C. The Earth is exerting the same pull on both the
Shuttle and its passengers.
D. The Earth is too far away to have a measurable
gravitational effect.
Forces
Standardized Test Prep
Reading Skills, continued
7. When the Shuttle is orbiting, it is in constant motion
around the Earth. Why isn’t this motion experienced as
weight?
A. There is no net force acting on the Shuttle.
B. The Shuttle’s mass is not large enough to exert a
measurable gravitational pull.
C. The Earth is exerting the same pull on both the
Shuttle and its passengers.
D. The Earth is too far away to have a measurable
gravitational effect.
Forces
Standardized Test Prep
Reading Skills, continued
8. Why can the Shuttle provide microgravity only after it
achieves orbit?
Forces
Standardized Test Prep
Reading Skills, continued
8. Why can the Shuttle provide microgravity only after it
achieves orbit?
Answer: Because before that point and after it takes off, the
Shuttle is accelerating, so there is a net force on it that
is also experienced by the objects within it.
Forces
Standardized Test Prep
Interpreting Graphics
The following graph charts the speeds of three objects
in motion. Use this graph to answer questions 9 and 10.
Forces
Standardized Test Prep
Interpreting Graphics, continued
9. At the 1 s mark,
which objects have
equal momentum?
A. the bicycle and
the rock
B. the rock and the
bowling ball
C. the bowling ball
and the bicycle
D. All three objects
have the same
momentum.
Forces
Standardized Test Prep
Interpreting Graphics, continued
9. At the 1 s mark,
which objects have
equal momentum?
A. the bicycle and
the rock
B. the rock and the
bowling ball
C. the bowling ball
and the bicycle
D. All three objects
have the same
momentum.
Forces
Standardized Test Prep
Interpreting Graphics, continued
10. At the 3 s mark,
which object or
objects have a net
force acting on them?
F.
H.
G.
I.
the bicycle
the bowling ball
the rock
the bicycle and
the bowling ball
Forces
Standardized Test Prep
Interpreting Graphics, continued
10. At the 3 s mark,
which object or
objects have a net
force acting on them?
F.
H.
G.
I.
the bicycle
the bowling ball
the rock
the bicycle and
the bowling ball
Forces
Standardized Test Prep
Interpreting Graphics, continued
The following graphic shows a long jumper making a
jump from west to east. Use this graphic to answer
questions 11 and 12.
Forces
Standardized Test Prep
Interpreting Graphics, continued
11. In what direction or directions is the net force acting on the jumper
between 0.5 s and 2 s?
A. first up and to the east, then down and to the west
B. first up and to the east, then down and to the east
C. up and to the east
D. down and to the west
Forces
Standardized Test Prep
Interpreting Graphics, continued
11. In what direction or directions is the net force acting on the jumper
between 0.5 s and 2 s?
A. first up and to the east, then down and to the west
B. first up and to the east, then down and to the east
C. up and to the east
D. down and to the west
Forces
Standardized Test Prep
Interpreting Graphics, continued
12. When the long jumper jumps, Earth exerts a force that moves him
up and to the east. Since there is a reaction force exerted on Earth,
why doesn’t Earth move the same distance down and to the west?
Forces
Standardized Test Prep
Interpreting Graphics, continued
12. When the long jumper jumps, Earth exerts a force that moves him
up and to the east. Since there is a reaction force exerted on Earth,
why doesn’t Earth move the same distance down and to the west?
Answer: The acceleration of Earth is force divided by mass, and since
Earth’s mass is so large, the resulting acceleration of Earth is
very small.