Name Class Date
Skills Worksheet
Directed Reading B
Section: Newton’s Laws of Motion
1. In 1686, what did Sir Issac Newton explain with his three laws of motion?
Newton’s First Law
2. What is Newton’s first law of motion?
3. Which of Newton’s laws of motion describes the motion of an object that has a net force of 0?
4. What are two examples of objects at rest?
5. How could an unbalanced force work on a chair at rest on the floor to make it slide across the room?
6. According to Newton’s first law of motion, what will happen to the motion of objects moving with a certain velocity unless an unbalanced force acts on them?
7. If you were in a bumper car that stopped abruptly when it hit another car, would you continue to move forward? Explain your answer.
8. What unbalanced force acts to stop a desk that is sliding across a floor?
Directed Reading B continued
9. What does friction do to the motion of objects?
10. What is Newton’s first law sometimes called?
11. What is the tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction until an outside force acts on the object?
12. Why is it easier to change the motion of an object with a small mass than it is to change the motion of an object with a large mass?
Newton’s second Law of Motion
13. What is Newton’s second law of motion?
14. What happens to the acceleration of an object if the force on the object stays the same as its mass decreases?
15. What happens to the acceleration of an object if the force on the object increases?
16. What is the relationship between an object’s acceleration and the direction of the force on the object?
Directed Reading B continued
17. Why would a cart start moving faster if you gave it a hard push than if you gave it a soft push?
Newton’s Third Law of Motion
18. What is Newton’s third law of motion?
19. Explain why Newton’s third law can be stated as “all forces act in pairs.”
20. What action and reaction forces are present when you are sitting on a chair?
21. Since all forces act in pairs, what happens whenever a force is exerted?
22. When a ball falls to Earth, why is it hard to see the effect of the reaction force exerted by the ball on Earth?
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Name Class Date
Skills Worksheet
Vocabulary and Section Summary B
Gravity: A Force of Attraction
Vocabulary
After you finish reading the section, try this puzzle!
Oh no! Penny Punster’s computer mixed up her physical science dictionary with her dictionary of puns. The computer paired the terms related to forces with her goofy definitions, and it paired her pun-related terms with the real definitions. Help Penny unscramble the mismatched pairs and get her dictionaries back in order.
1. static: friction that disappears when an object starts moving
2. grubby tea: force of attraction between objects due to mass
3. you never sell: applies to all objects in the universe
4. wade: measure of the force of gravity on an object
5. mace: amount of matter in an object
SECTION SUMMARY
Read the following section summary.
• Gravity is a force of attraction between objects that is due to their masses. Gravity can be an unbalanced force that causes changes in velocity.
• Gravity holds the solar system together.
• The law of universal gravitation states that all objects attract each other through gravitational force and that the magnitude of this force depends on the objects’ masses and the distance between them.
• Mass is the amount of matter in an object. Weight is a measure of the
gravitational force on an object.
• Gravity is often balanced by elastic forces due to tension or compression.
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