True/False
Indicate whether the statement is true or false.

1.

A speed that does not vary is called average speed.

2.

Acceleration is defined as the rate of change of position.

3.

The combination of all forces acting on an object is the net force.

4.

Velocity changes when the direction of motion changes.

5.

The more mass an object has, the greater its inertia is.

6.

Work equals force times distance (W = F ´ d).

7.

Newton's third law says that an object in motion is slowed down by gravity.

8.

Friction always acts in a direction opposite of motion.

9.

When you walk, you push on the sidewalk, and the sidewalk pushes on you with equal force.

10.

The relationship of force and acceleration of an object is explained using Newton’s first law of motion.

Multiple Choice
Identify the choice that best completes the statement or answers the question.

11.

A soccer ball takes 20 s to roll 10 m. What is the average speed of the soccer ball?
 a. 200 m/s c. 2 m/s b. 5 m/s d. 0.5 m/s

12.

When an object is at rest, what is its speed?
 a. 2 m/s c. 1 m/s b. 3 m/s d. 0 m/s

13.

Which describes how velocity changes with time?
 a. acceleration c. gravity b. average speed d. inertia

14.

A person in a head-on car collision who is not wearing a seat belt continues to move forward at the original speed of the car because of ____.
 a. friction c. gravity b. inertia d. weight

15.

If you want to calculate the acceleration of a car, you should ____ the change in speed of the car by the time interval.
 a. add c. divide b. decrease d. multiply

16.

What is the term for speed at any instant in time?
 a. instantaneous speed c. constant speed b. variable speed d. average speed

17.

Newton’s first law of motion states that an object stays at rest unless a(n) ____ acts on it.
 a. balanced force c. gravitational force b. unbalanced force d. strong force

18.

Which one of the following objects has the greatest inertia?
 a. baseball c. pencil b. bowling ball d. toothpick

19.

A force is which one of these?
 a. a push c. a push or pull b. a pull d. none of these

20.

Force is measured in which units?
 a. kilograms c. newtons b. degrees d. m/s2

21.

For an ideal machine, the work in is equal to ____.
 a. a fraction of the work out c. the work out b. twice the work out d. half the work out

22.

____ is done only when an object moves in the direction of the applied force.
 a. Friction c. Effort b. Work d. Inertia

23.

A force is exerted on a box and an equal and opposite force is exerted by the box. What explains this?
 a. conservation of energy c. Newton’s second law of motion b. Newton’s first law of motion d. Newton’s third law of motion

24.

A(n) ____ is a rod or plank that pivots about a fixed point.
 a. wedge c. pulley b. axle d. lever

25.

According to Newton’s second law of motion, ____.
 a. a = Fnet/m c. a = m/Fnet b. a = m X Fnet X s d. a = s X m

Matching

Match the units with the descriptions below.
 a. m/s2 d. m/s b. J e. m c. N

26.

the unit of force

27.

the unit of average speed

28.

the unit of work

29.

the unit of acceleration

30.

the unit of distance

Match the terms with the statements below.
 a. pulley d. Newton’s second law b. wedge e. Newton’s third law c. Newton’s first law

31.

The harder you pedal a bicycle, the faster it will go.

32.

the main reason a person can jump off the ground

33.

34.

the cord on a window blind

35.

A hockey puck will slide across ice for a long time when hit.

Completion
Complete each statement.

36.

According to Newton’s Third Law, forces always occur in equal but ____________________ pairs.

37.

The ____________________ is the combination of all the forces acting on an object.

38.

____________________ measures the quantity of matter in an object.

39.

The acceleration of an object can be shown on a(n) ____________________ graph.

40.

Machines can change the ____________________ of the force you apply and the ____________________ of the force.

41.

The force that resists motion between two objects that are in contact with each other is ____________________.

42.

According to Newton’s first law of motion, an object moving in a straight line at constant speed will continue doing that unless acted on by a ____________________.

43.

A rocket blasting off is best represented by Newton’s ____________________ law of motion.

44.

To calculate ____________________ you divide distance traveled by the time it takes to travel that distance.

45.

A(n) ____________________ is a sloped surface, sometimes called a ramp, that allows you to lift a heavy load by using less force over a greater distance.

46.

Why does work in fail to equal work out for a real machine?

47.

What is the purpose of a machine?

48.

Can an object’s acceleration be a negative number? Why or why not?

49.

50.

If forces occur in equal but opposite pairs, how can anything ever move?

51.

Two crates, one heavy and one light, are at rest on a waxed floor. Which crate will need a greater force to provide the same acceleration? Use the concept of inertia to explain your answer.

52.

List the forces that act on a tennis ball during a game and explain how each force affects the tennis ball.

53.

All objects should fall at the same rate. But a feather falls at a slower rate than a marble. Explain why this is so.

54.

Explain the role of friction in walking on a sidewalk versus walking on a sidewalk covered with ice.

55.

You sit on a rock. Your weight is a force acting on the rock. What force acts on you?

56.

Use Newton's second law to explain why a space shuttle remains in orbit.

57.

In what two ways can machines make work easier?

58.

How is acceleration related to change in speed?

Problem

59.

A swimmer swims 20 m in 40 s. What is the swimmer’s average speed?

60.

A person is traveling at 20 m/s in a car when the car hits a tree. The person comes to a complete stop in 0.4 seconds. What was the person’s acceleration?