Transcript ch11_stp_as - Doral Academy Preparatory

Motion
Motion
Preview
• Understanding Concepts
• Reading Skills
• Interpreting Graphics
Standardized Test Prep
Motion
Standardized Test Prep
Understanding Concepts
1. A meteorologist describes a tropical storm as traveling
northwest at 50 mi/h. Which attribute of the storm’s
motion has the meteorologist described?
A. force
B. acceleration
C. velocity
D. displacement
Motion
Standardized Test Prep
Understanding Concepts
1. A meteorologist describes a tropical storm as traveling
northwest at 50 mi/h. Which attribute of the storm’s
motion has the meteorologist described?
A. force
B. acceleration
C. velocity
D. displacement
Motion
Standardized Test Prep
Understanding Concepts, continued
2. Which of the following must be applied to move an
object at rest, such as a large rock?
F. static friction
G. kinetic friction
H. balanced forces
I. unbalanced forces
Motion
Standardized Test Prep
Understanding Concepts, continued
2. Which of the following must be applied to move an
object at rest, such as a large rock?
F. static friction
G. kinetic friction
H. balanced forces
I. unbalanced forces
Motion
Standardized Test Prep
Understanding Concepts, continued
3. A fish swimming at a constant speed of 0.5 m/s
suddenly notices a shark appear behind it. Five
seconds later, the fish is swimming in the same
direction at a speed of 2.5 m/s. What was the fish’s
average acceleration?
A. 0.4 m/s2
B. 0.6 m/s2
C. 1.7 m/s2
D. 2.5 m/s2
Motion
Standardized Test Prep
Understanding Concepts, continued
3. A fish swimming at a constant speed of 0.5 m/s
suddenly notices a shark appear behind it. Five
seconds later, the fish is swimming in the same
direction at a speed of 2.5 m/s. What was the fish’s
average acceleration?
A. 0.4 m/s2
B. 0.6 m/s2
C. 1.7 m/s2
D. 2.5 m/s2
Motion
Standardized Test Prep
Understanding Concepts, continued
4. Bowling lanes are made as smooth as possible in order
to minimize kinetic friction. Why is this desirable in a
bowling lane?
Motion
Standardized Test Prep
Understanding Concepts, continued
4. Bowling lanes are made as smooth as possible in order
to minimize kinetic friction. Why is this desirable in a
bowling lane?
Answer: The less kinetic friction that is exerted on a
bowling ball, the more speed a bowling ball will be able
to maintain as it rolls down a lane. The faster the ball is
going, the more pins it is likely to knock down.
Motion
Standardized Test Prep
Understanding Concepts, continued
5. Two amateur entomologists are observing the
movement of a beetle traveling in a straight line across
a driveway. Every 10 s, they measure the distance that
the beetle has traveled. Afterward, they create a graph
of the beetle’s motion, with distance on the y-axis and
time on the x-axis. What does the slope of their graph
represent?
Motion
Standardized Test Prep
Understanding Concepts, continued
5. Two amateur entomologists are observing the
movement of a beetle traveling in a straight line across
a driveway. Every 10 s, they measure the distance that
the beetle has traveled. Afterward, they create a graph
of the beetle’s motion, with distance on the y-axis and
time on the x-axis. What does the slope of their graph
represent?
Answer: The slope of the graph is distance divided by time,
which gives the average speed of the beetle during that
time interval.
Motion
Standardized Test Prep
Reading Skills
MOVING BY FRICTION
Friction is usually thought of as interfering with motion,
but there are many sorts of movement that depend on
friction. When any two surfaces move against each other,
friction exerts force in a direction opposite to the direction of
push. Runners use the energy in their leg muscles to push
backward on the ground with one foot. The ground forces
their body forward. If not for the friction between the running
shoes and the ground, their feet would slip backward
against the ground instead.
Motion
Standardized Test Prep
Reading Skills, continued
MOVING BY FRICTION, continued
The friction between two surfaces before they move is
called static friction. After the two surfaces begin moving
against each other, the frictional force lessens; the force is
then called kinetic friction. Once a runner’s foot begins to
slip, the frictional force decreases, as does the force
exerted on the runner in the opposite direction—toward the
finish line! Runners need friction to move forward.
Motion
Standardized Test Prep
Reading Skills, continued
6. When a runner’s shoe slips against the ground, what is
the effect on the net force affecting the runner?
F. The net force pushing the runner forward increases.
G. The net force pushing the runner forward decreases.
H. The net force pushing the runner toward the ground
increases.
I. The net force pushing the runner toward the ground
decreases.
Motion
Standardized Test Prep
Reading Skills, continued
6. When a runner’s shoe slips against the ground, what is
the effect on the net force affecting the runner?
F. The net force pushing the runner forward increases.
G. The net force pushing the runner forward decreases.
H. The net force pushing the runner toward the ground
increases.
I. The net force pushing the runner toward the ground
decreases.
Motion
Standardized Test Prep
Reading Skills, continued
7. A runner decides to get new running shoes because the
old ones are slipping too much against the ground.
What should the runner look for in a new pair of shoes?
Motion
Standardized Test Prep
Reading Skills, continued
7. A runner decides to get new running shoes because the
old ones are slipping too much against the ground.
What should the runner look for in a new pair of shoes?
Answer: More friction with the ground is desirable, so the
bottoms of new running shoes should have a rougher
surface, and be less worn out, than the old ones.
Motion
Standardized Test Prep
Interpreting Graphics
The graphic below shows four motorcycle racers on the
last 800 m of a track. Use this graphic to answer
questions 8 and 9.
Motion
Standardized Test Prep
Interpreting Graphics, continued
8. Assuming that each motorcycle continues to travel toward the finish
line at the given constant velocity above, which will occur first?
A. Cycle A passes Cycle B.
B. Cycle B passes Cycle C.
C. Cycle B crosses the finish line.
D. Cycle D crosses the finish line.
Motion
Standardized Test Prep
Interpreting Graphics, continued
8. Assuming that each motorcycle continues to travel toward the finish
line at the given constant velocity above, which will occur first?
A. Cycle A passes Cycle B.
B. Cycle B passes Cycle C.
C. Cycle B crosses the finish line.
D. Cycle D crosses the finish line.
Motion
Standardized Test Prep
Interpreting Graphics, continued
9. From Cycle A’s frame of reference, which cycle or cycles are
moving toward Cycle A the fastest?
F. Cycle B appears to be moving the fastest.
G. Cycle D appears to be moving the fastest.
H. Cycles B and D appear to be moving at the same speed.
I. All three cycles appear to be moving at the same speed.
Motion
Standardized Test Prep
Interpreting Graphics, continued
9. From Cycle A’s frame of reference, which cycle or cycles are
moving toward Cycle A the fastest?
F. Cycle B appears to be moving the fastest.
G. Cycle D appears to be moving the fastest.
H. Cycles B and D appear to be moving at the same speed.
I. All three cycles appear to be moving at the same speed.
Motion
Standardized Test Prep
Interpreting Graphics, continued
The graph below shows how long it took for two
vehicles to stop from a speed of 30 m/s. Use the graph
to answer questions 10 and 11.
Motion
Standardized Test Prep
Interpreting Graphics, continued
10. What can we conclude from
the graph about the car and
the truck?
A. The truck’s final velocity is
greater than the car’s.
B. The car’s final velocity is
greater than the truck’s.
C. The truck’s acceleration
has greater absolute value
than the car’s.
D. The car’s acceleration has
greater absolute value
than the truck’s.
Motion
Standardized Test Prep
Interpreting Graphics, continued
10. What can we conclude from
the graph about the car and
the truck?
A. The truck’s final velocity is
greater than the car’s.
B. The car’s final velocity is
greater than the truck’s.
C. The truck’s acceleration
has greater absolute value
than the car’s.
D. The car’s acceleration has
greater absolute value
than the truck’s.
Motion
Standardized Test Prep
Interpreting Graphics, continued
11. If the slope of the two
lines remained the same,
how long would it take
each vehicle to coast to a
stop from an initial
velocity of 100 mph?
Motion
Standardized Test Prep
Interpreting Graphics, continued
11. If the slope of the two
lines remained the same,
how long would it take
each vehicle to coast to a
stop from an initial
velocity of 100 mph?
Answer: Based on the slope of each
line and the equation y = mx + b,
the car would take 27 s, and the
truck 40 s, to coast to a stop.