Download Physical Science Chapter 3

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Forces
Physical Science
Chapter 3
Forces
1.
Define the following terms:
a. force=
a.
spring scale=
b.
Newtons=
c.
balanced force=
d.
unbalanced force=
e.
net force=
2. How do forces affect the motion of an object?
3. How do you measure forces?
4. Why does a heavy chair not move by itself? ?
5. Is the following sentence true or false? A force can act to cause an object at rest to move or it can
accelerate an object that is already moving.
6. What tool do you use to measure force? ?
7. How can a force change the motion of an object that is already moving?
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8. What is the unit of force? ?
9. Circle the letter of the best answer. What force causes a 1 kg mass to accelerate at a rate of
meter per second each second.
a.
1 kg/ms2
b. 1 kgm
c. 1 kg/s
d. 1 newton
10. What is the difference between a balanced force and an unbalanced force? ?
11. If an unbalanced force acts on a ball, the ball will always move in which direction? ?
12. How do balance and unbalance forces affect the motion of an object?
13. What forces control the motion of everyday objects?
14. Draw a diagram to represent a foot kicking a resting soccer ball. Use arrows to represent the
force applied to the ball and to show how the ball moves after it is kicked.
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Friction
15. Define the following terms:
a. friction=
f.
static friction=
g.
sliding friction=
h.
rolling friction =
i.
fluid friction =
j.
air resistance=
10. What are the four main types of friction?
11. Complete the sentences using: friction heat little motion resists
a. The rubbing of one object against another is
b. Friction is a force that
c. Every
, or works against, motion.
that takes place on Earth is affected by friction.
d. Smooth surfaces such as ice provide very
e. Friction makes
.
friction.
.
12. How is heat created with friction?
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13. Compare the strengths of static, sliding and rolling friction.
14. How do gravity and air resistance affect a falling object?
15. Complete the table below about friction forces.
Types of Friction Forces
Friction Force
Example
Static
Pushing a book along your desk
Rolling
16. How is friction reduced between the moving parts inside a car engine?
17. Outside wooden steps may get slippery when they are wet. How could you make them less
slippery?
18. Why is less force is needed to keep an object moving than to start the object in motion?
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Projectile Motion
19. Define the following terms:
a. gravity=
k.
law of universal gravitation=
l.
projectile motion=
20. What two factors affect gravity?
21. How is weight related to gravity?
22. Why does the moon have less gravity than Earth?
23. On Earth, how fast do object accelerate due to gravity?
24. If the distance between the two objects doubles, how does this affect the force of gravity
between them? ?
25. Describe the relationship between the masses of two objects and the force of gravity between
them. ?
26. If two objects each have a mass of 10 kg, then the force of gravity between them
a. is 100 kg.
b. is constant.
c. depends only on their masses.
d. is greater when they are closer together.
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27. Why don’t larger object fall faster?
28. Why does projectile motion follow a curved path?
29. How might knowledge of projectile motion help you shoot baskets in basketball? ?
30. Give three examples of projectile motion.
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Newton’s Laws of Motion
31. Define the following terms:
a. inertia=
32. What is Newton’s first law of motion?
33. What is another name for the Newton’s first law of motion?
34. Give an example of Newton’s first law of motion at work?
35. Indicate if the following sentences are true or false.
a. According to Newton’s first law of motion, an objects state of motion does not change
as long as the net force acting on it is zero.
b. Inertia is the tendency of an object in motion to slow down and come to a complete
stop if it travels far enough in the same direction.
36. What is Newton’s second law of motion?
a. What does the “F” stand for in Newton’s second law?
b. What does the “m” stand for in Newton’s second law?
c. What does the “a” stand for in Newton’s second law?
37. What are the three ways to represent the formula for Newton’s 2nd Law?
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38. Directions: use the Newton’s Second Law of Motion to solve the following problems.
Show Work!!
a. Tori applies a force of 20 newtons to move a bookcase with a mass of 40 kg. What is the
acceleration of the bookcase?
b. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. Determine the mass.
c. An object is accelerating at 2 m/s2. If the net force is tripled and the mass is doubled,
then what is the new acceleration?
d. An object is accelerating at 2 m/s2. If the net force is tripled and the mass is halved, then
what is the new acceleration?
e. What is the upward acceleration of a helicopter with a mass of 5000 kg if a force of
10,000 N acts on it in an upward direction?
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39. Indicate if the following sentences are true or false.
a. The acceleration of an object is always in the same direction as the net force acting on
the object.
b. If the same force acts upon two objects with different masses, the acceleration will be
greater for the object with the greater mass.
40. What is Newton’s Third Law of Motion?
41. What are the forces in the 3rd law?
42. Why don’t action and reaction forces cancel each other out?
43. Is the following statement true of false? Action-reaction forces do not cancel each other
because the action force is always greater than the reaction force.
44. Give an example of this law in action.
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Momentum
45. Define the following terms:
a. momentum=
46. What is the momentum formula?
47. Circle the letter of each factor that affects the momentum of a moving object.
a. Mass
c. Shape
b. Volume
d. Velocity
48. What is needed for an object to have a large momentum?
49. What is the momentum of an 80 kg runner moving at the speed of 2.5 m/s?
50. If you double the velocity of a moving object, how is its momentum affected?
51. If two identical objects are moving at different velocities, the object that is moving faster will
have (
greater
or
lesser
) momentum.
52. Your in-line skates are sitting in a box on a shelf in the closet. What is their momentum?
53. What is the law of conservation of momentum?
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Name:
54. According to the law of conservation of mass, what happens to the total momentum of a
system if no net force acts on the system?
55. Create a diagram to illustrate the transfer and conservation of momentum when a moving
object collides with a stationary object.
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