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Ch. 2 Test Practice
Topics covered: speed & velocity, frame of reference, Newton’s 1st law, forces & free-body
diagrams
Format of test: multiple choice, short answer and calculations
Choose the best answer:
1. The force that one surface exerts on another when the two rub against each other is called
a. friction.
b. acceleration.
c. inertia.
d. gravity.
2. If the net force on an object is zero then the object has
a. balanced forces.
b. action forces.
c. reaction forces.
3. The greater the mass of an object,
a. the easier the object starts moving.
c. the greater its inertia.
d. unbalanced forces.
b. the more space it takes up.
d. the more balanced it is.
4. The tendency of an object to resist any change in its motion is known as
a. balance.
b. force.
c. inertia.
d. mass.
e. friction
5. If the net force acting on a stationary object is zero, then the object will
a. begin moving backwards.
b. accelerate in the direction of the strongest force.
c. remain at rest.
d. decelerate at a steady rate of speed.
6. When two equal forces act on the same object in opposite directions, the net force is
a. equal to each of the forces.
b. zero.
c. smaller than either force.
d. greater than either force.
7. In physical science, a push or a pull is called a(n)
a. motion.
b. acceleration.
c. inertia.
d. force.
8. What is a difference between an object’s speed and velocity?
a. Speed includes direction as well as the rate of travel
b. Velocity includes time during which travel occurred
c. Velocity includes the direction of travel whereas speed does not
d. There is no difference.
9. In the absence of an external force, a moving object will
a) stop immediately.
b) slow down and eventually come to a stop.
c) go faster and faster.
d) move with constant velocity
10. You are standing in a moving bus, facing forward, and you suddenly fall forward as the bus comes to an immediate
stop. What force caused you to fall forward?
a) gravity
b) normal force due to contact with the floor of the bus
c) force due to friction between you and the floor
d) There is not a force leading to your fall.
11. A book is sitting on a dashboard of a car that's stopped at a traffic light. As the car starts to move forward, the book
slides off the dashboard. Pick the most correct explanation.
a. There was grease on the dashboard
b. The object had inertia.
c. A supernatural force took over.
d. Friction made the book move backward.
12. When a woman stands with two feet on a scale, the scale reads 300 N. When she lifts one foot, the scale reads
a) 0 N
b) 150 N
c) 300 N
d) 600 N
13. A person is pulling west with 35 N of force against a person pulling east with 15 N of force. What is the net force?
a) 50 N west
b) 50 N east
c) 20 N east
d) 20 N west
14. Two people are pulling a refrigerator into a garage. One person is pulling south with 30 N of force, while the other
person is pulling south with 25 N of force. What is the net force?
a) 5 N south
b) 5 N north
c) 55 N north
d) 55 N south
15. Which of the following statements correctly states Newton’s first law of motion?
a) Every object retains its state of rest or its state of accelerated straight line motion unless acted upon by an
unbalanced force.
b) Every object retains its state of rest or its state of uniform straight-line motion unless acted upon by a
balanced force.
c) Every object retains its state of rest or its state of uniform straight-line motion unless acted upon by an
unbalanced force.
d) None of the above are correct.
16. The term inertia means which of the following? The tendency of an object to
a) maintain its mass.
b) remain in motion.
c) remain in rest or motion.
d) stop the motion of other objects.
17. If the forces on an object are balanced, the object will
a) remain at rest if initially at rest.
b) Continue moving in a straight line if initially moving in a straight line.
c) both a and b
d) neither a nor b
18. Which of the following statements are true of both weight and mass?
a) Weight is a force, mass is a measure of inertia
b) Mass depends on gravity, weight does not
c) Heavier objects weigh more than light objects.
d) Gravity is necessary to measure both weight and mass.
e) all of the above
19. What is the unit of weight in the metric system?
a) Kilogram
b) newton
c) pound
d) meters per second
20. Which of the following indicate that an object has been subjected to an unbalanced force?
a) The object speeds up.
b) The object slows down.
c) The object changes direction.
d) Any of the above.
21. Newton’s first law of motion states than an object’s motion will not change unless
a) the net force acting on it is greater than zero.
c) its inertia is stronger than the applied force.
b) a force continues to be applied to the object.
d) the object has no inertia.
22. Overcoming an object’s inertia always requires a(n)
a) large mass.
b) massive force.
c) unbalanced force.
d) two of the above
23. It is more difficult to start a 50-kg box sliding across the floor than a 5-kg box because the 50-kg box has greater
a) size.
b) inertia.
c) volume.
d) velocity.
24. Once an object starts moving along a clear path, it would keep moving at the same velocity if it were not for
a) inertia.
b) friction.
c) an unbalanced force.
d) two of the above
25. An object’s velocity will not change unless it is acted on by a(n)
a) net force.
b) strong force.
c) unbalanced force.
d) opposite but equal force.
26. The direction of a moving object will not change if the net force acting on it is
a) greater than zero.
b) less than zero.
c) zero.
d) two of the above
27. Determine if the following statements are true or false.
_____ a. Inertia is the tendency of an object to resist a change in motion.
_____ b. Newton’s first law of motion is also called the law of acceleration.
_____ c. The inertia of an object is determined by its speed.
_____ d. The speed of an object changes only when it is acted on by an unbalanced force.
_____ e. A stationary object resists movement only because of gravity.
_____ f. The tendency of an object to resist a change in motion depends on its mass.
_____ g. If the net force acting on an object is zero, its inertia is also zero.
_____ h. When you are moving at a high rate of speed, inertia makes it hard to stop.
_____ i. Newton’s first law of motion applies only to objects that are already moving.
29. Match each definition with the correct term.
Definitions
Terms
__________ a. combination of all the forces acting on an object
inertia
__________ b. force that opposes the motion of any object
unbalanced force
__________ c. an object’s motion will not change unless an unbalanced force acts on it
friction
__________ d. factor that determines the inertia of an object
law of inertia
__________ e. type of force needed to overcome inertia of an object
mass
__________ f. tendency of an object to resist a change in motion
net force
30. Which of the following statements are true of inertia? List all that apply.
a) Inertia is a force.
b) Inertia is a force which keeps stationary objects at rest and moving objects in motion at constant velocity.
c) Inertia is a force which brings all objects to a rest position.
d) All objects have inertia.
e) A more massive object has more inertia than a less massive object.
f) Fast-moving objects have more inertia than slow-moving objects.
g) An object would not have any inertia in a gravity-free environment (if there is such a place).
h) Inertia is the tendency of all objects to resist motion and ultimately stop.
i) In a gravity-free environment (should there be one), a person with a lot of inertia would have the same ability to
make a turn as a person with a small amount of inertia.
31. Which of the following statements are true of an object that experiences balanced or unbalanced forces)?
List all that apply.
a) If a person is moving to the right, then the forces acting upon it are NOT balanced.
b) A balance of forces is demonstrated by an object which is slowing to a stop.
c) It would take an unbalanced force to keep an object in motion.
d) If an object is moving with a constant speed in a circle, then the forces acting upon the object are balanced.
e) If an object is accelerating at a constant rate of acceleration, then the forces acting upon the object are balanced.
f) It is NOT possible for just three forces to be acting upon an object and they still balance each other.
g) Balanced forces cause stationary objects to remain at rest and moving objects to come to rest.
h) Unbalanced forces cause objects to move.
32. Consider Newton's first law of motion to determine which of the following statements are true? List all that apply.
a) Newton's first law of motion is applicable to both moving and nonmoving objects.
b) If a football is moving upwards and rightwards towards the peak of its trajectory, then there are both rightwards
and upwards forces acting upon it.
c) It would take an unbalanced force to keep an object in motion.
d) If an object is at rest, then there are no forces acting upon the object.
e) It would take an unbalanced force to keep an object in motion at a constant velocity.
f) It is the natural tendency of all objects to eventually come to a rest position.
g) A pendulum bob is set into its usual back-and-forth periodic motion. After some time (perhaps 10 minutes), the
pendulum bob comes to a rest position. This is best explained by the idea of inertia - all objects eventually resist
motion.
h) If a 3-kg rock is thrown at a speed of 2 m/s in a gravity-free environment (presuming one could be found), then an
unbalanced force of 6 N would be required to keep the rock moving at a constant speed.
i) It would take an unbalanced force to cause an object to accelerate from rest.
33. Which one(s) of the following force diagrams depict an object moving to the right with a constant speed? List all that
apply.
34. Construct free-body diagrams for the following physical situations at the instant in time for which they are
described. As is always done in free-body diagrams, label the forces according to type and draw the arrows such
that their length reflects the magnitude of the force.
a) A book at rest on top of a table.
b) A student is pushing lightly upon a large box in an attempt to push it to the right across the floor, but the box
fails to move.
c) A book is being pushed to the right across a table surface and speeding up in the direction of the push.
d) An air track glider is gliding to the left at constant velocity.
Calculations: Be sure to show your work and give answers with correct significant figures and units.
1. The race car was moving for 3.70 hours and during that time moved 500. miles east. What is the
speed? What is the velocity?
2. Mike is driving west on I-80 for 1.50 hours at a speed of 70.0 miles per hour. What is his distance?
3. If you are traveling at 75. km/h how long will it take to travel 32. km?
4. A man walks 7.0 km East in 2.0 hours and then 2.5 km West in 1.0 hour.
a) What is the man's average speed for the whole journey?
b) What is the man's average velocity for the whole journey?
5. A train travels along a straight line at a constant speed of 60.0 mi/h for 4.00 hr and then another
3.00 hr in the same direction at a constant speed of 80.0 mi/h. What is the average speed of the
train for the whole journey?
6. You need to get to class, 200 meters away, and you can only walk in the hallways at about 1.5
m/s. How much time will it take to get to your class?
7. If you shout into the Grand Canyon, your voice travels at the speed of sound (340. m/s) to the
bottom of the canyon and back, and you hear an echo. How deep is the Grand Canyon at a spot
where you can hear your echo 5.20 seconds after you shout?
Short answer: Be sure to include “solid” physics in your explanations.
1. An airplane has a velocity, with respect to the air, of 825 km/hr northward. What is the velocity of
the airplane with respect to the ground if the wind is blowing with a velocity of 35 km/hr
southward.
2. If the speedometer of a car reads a constant speed of 50 km/hr, can you say that the car has a
constant velocity? Why or why not?
3. Roll a bowling ball down a lane and you’ll find it moves slightly slower with time. Does this violate
Newton’s law of inertia?
4. As you stand at rest on a floor, does the floor exert an upward force against your feet? If so, what
exactly is this force?
5. Why do you lurch forward in a bus that suddenly stops? Why do you lurch backward when it picks
up speed?