Section 1 Review page 371
1. Explain the relationship between motion and frame of reference. When an object
changes position with respect to a frame of reference the object is in motion.
2. Identify the following measurements as speed or velocity
a. 88 km/h
speed
b. 9 m/s to the west velocity
c. 18 m/s down
velocity
d. 10 m/s
speed
3. Describe the measurements necessary to find the average speed of a high school track
athlete. Measure the distance the athlete travels and the time required to travel that distance
4. Determine the unit of a caterpillar’s speed if you measure the distance in centimeters
(cm) and the time it takes to travel that distance in minutes (min). How would you
graph the data? cm/min; time on the horizontal axis and distance on the vertical axis
5. Imagine that you could ride a baseball that is hit hard enough for a home run. If the
baseball is your frame of reference, what does the Earth appear to do? The Earth
appears to travel backwards for the distance baseball travels and at the speed at which the
baseball travels.
6. How much time does it take for a student running at an average speed of 5.00 m/s to
cover a distance of 2.00 km? 2 km = 2000 meters
2000 meters/ 5 m/sec = 4.00 x 102 sec or 6.67 minutes
Section 2 Review page 377
1. Explain why circular motion includes continuous acceleration even when the speed does
not change. Circular motion is an acceleration because the velocity is changing. Velocity
includes both speed and direction. When an object moves in a circle, its direction is
changing.
2. Identify the straight-line acceleration below as either speeding up or slowing down.
a. 5.7 m/s2 speeding up
b. -29.8 m/s2 slowing down
c. -2.43 m/s2 slowing down
d. 9.8 m/s2 speeding up
3. Graph the velocity vs. time from 0 s to 10 s of a car that accelerates from a standstill at a
constant rate of 1.5 m/s2.
Meters
Time
4. Interpreting Data Joshua skates in a straight line at a constant speed for 1 min, then
begins going in circles at the same rate of speed, and finally begins to increase speed.
When is he accelerating? Explain your answer. He is accelerating both when he is going
in circles at the same rate of speed and when he is increasing speed.
Math Skills
5. What is the final speed of a skater who accelerates at a rate of 2.0 m/s2 from rest for 3.5
m/s2? 2.0 * 3.5 = 7 m/s
6. Graph the velocity of a car accelerating at a uniform rate from 7.0 m/s to 12.0 m/s in 2.0
s. Calculate the acceleration.
Should be a straight line from 7.0 m/s at 0 s line of time to 12 m/s at the 2.0 line of time
Section 3 Review page 385
1. List the fundamental forces of nature. Gravity, electromagnetic forces, weak nuclear
forces, strong nuclear forces
2. Describe a situation in which unbalanced forces are acting on an object. What is the net
force on the object, and how does the net force change the motion of the object? A
baseball falling to the Earth is an example of a situation involving unbalance forces. The net
force is the force of gravity combined with kinetic friction. The net force caused the baseball
to fall to toward the Earth.
3. Identify the type of friction in each situation described below
a. Two students are pushing a box that is at rest static friction
b. The box pushed by the students is now sliding kinetic friction
c. The students put rollers under the box and push it forward rolling friction
4. Explain why driving on a road requires friction. How could you increase friction on an
icy road. Friction between the tires of the road enables the tires to push against the road and
vice versa so that the car experiences a net force and moves forward to make a turn.
To increase friction, on an icy road, you could put salt or sand on the road.
5. Understanding relationships. Describe three ways to decrease the force of friction
between two surfaces that are moving past each other. Lubricate the surface, smooth the
surface, or place ball bearings between surfaces
6. Analyzing ideas.When you wrap a sandwich in plastic food wrap to protect it, you must
first unroll the plastic wrap from the container and the wrap the plastic around the
sandwich. In both steps, you encounter friction. In each step, is friction helpful or not?
Explain your answer. The friction between your hand and the wrap help you pull the wrap.
Friction between the two parts is harmful because it slows down the wrap. When warping the
sandwich, the friction between the edges of the plastic is helpful, because it keeps the plastic
sticking to itself.
7. Interpreting Data. The force pulling a truck downhill is 2,000 N. What is the amount of
static friction acting on the truck if the truck does not move? If there is no acceleration,
the net force is zero.