# Science Chap13 Study Guide A

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b. gravity

### 2. Why is all matter affected by gravity? a. All matter has weight. b. All matter has size. c. All matter has volume. d. All matter has mass.

d. All matter has mass.

### 3. Why don't you notice smaller objects move toward each other due to gravity? a. The distance is too small. b. The distance is too large. c. Their masses are too small. d. Their masses are too large.

c. Their masses are too small.

### 4. What force must be overcome to lift objects or parts of your body? a. magnetic force b. gravitational force c. net force d. natural force

b. gravitational force

b. gravity

b. gravity

### 7. What law describes how gravitational force, mass, and distance are related? a. the law of conservation of gravity b. the law of conservation of mass c. the law of universal gravitation d. the law of universal mass

c. the law of universal gravitation

### 8. What does the law of universal gravitation apply to? a. everything in the universe b. only to Earth c. only to outer space d. only to the solar system

a. everything in the universe

c. It increases.

### 10. Why doesn't the sun's gravitational force affect you more than Earth's does? a. The sun has more velocity. b. Earth has more air pressure. c. Earth is moving faster. d. The sun is much farther away.

d. The sun is much farther away.

b. It decreases.

c. weight

d. mass

### 14. What happens to an object's mass when gravitational force is increased? a. It increases and then decreases. b. It does not change. c. It increases. d. It decreases.

b. It does not change.

### 15. What happens to an object if it is moved from Earth to Jupiter? a. Its weight and mass increase. b. Its weight and mass decrease. c. Its weigh increases and mass remains the same. d. Its mass increases and weight remains the same.

c. Its weigh increases and mass remains the same.

a. one-sixth

### 17. What is a static object? a. a moving object b. a nonmoving object c. a weightless object d. a massless object

b. a nonmoving object

### 18. Why doesn't a static object move downward? a. Gravity on the object is balanced by an upward force. b. Gravity does not pull on static objects. c. Static objects don't have weight. d. Static objects don't have mass.

a. Gravity on the object is balanced by an upward force.

### 1. Which scientist first thought that the amount of time it takes an object to fall does not depend on the object's mass? a. Isaac Newton b. Galileo Galilei c. Albert Einstein d. Marie Curie

b. Galileo Galilei

### 2. Why do objects fall to the ground at the same rate? a. Their acceleration is the same. b. Their masses are the same. c. Their weights are the same. d. Their sizes are the same.

a. Their acceleration is the same.

### 3. Why is a heavier object harder to accelerate than a lighter one? a. It has more mass. b. It has less mass. c. It is larger. d. It is harder to throw.

a. It has more mass.

b. acceleration

c. 9.8 m/s2

a. v = g x t

b. g

c. t

a. v

### 10. What is the term for a force that works against the motion of objects through air? a. gravity b. terminal velocity c. free fall d. air resistance

d. air resistance

### 11. Why does a flat sheet of paper fall more slowly than a crumbled sheet? a. Gravity exerts less force on a flat sheet. b. The crumbled paper is heavier. c. The flat paper is lighter. d. The flat paper has more air resistance.

d. The flat paper has more air resistance.

b. free fall

### 13. when a falling object stops accelerating a. terminal velocity b. free fall

a. terminal velocity

### 14. When you throw something, what do you call its curved path? a. terminal velocity b. projectile motion c. terminal motion d. projectile velocity

b. projectile motion

### 15. Why does the horizontal velocity of a ball remain the same after it leaves your hand? a. Your hand is still applying force to the ball. b. There are no forces that can change the ball's horizontal velocity. c. Your friend catches the ball before the horizontal velocity can change. d. There is no force of gravity acting on the ball.

b. There are no forces that can change the ball's horizontal velocity.

a. gravity

d. gravity

### 18. If you want to hit a target, where should you aim? a. at the target b. below the target c. above the target d. to either side of the target

c. above the target

### 19. When is an object orbiting? a. When it reaches terminal velocity. b. When it comes against air resistance. c. When it is moving around another object in space. d. When it moves in a straight line.

c. When it is moving around another object in space.

d. free fall

### 21. Which of the following is orbiting? a. a planet moving around the sun b. a plane in flight c. a balloon d. a rocket flying straight up

a. a planet moving around the sun

### 22. Which is NOT true of centripetal force? a. It is an unbalanced force. b. It can hold objects in nearly circular paths. c. It pushes outward. d. It means "a force toward the center."

c. It pushes outward.

a. gravity

### 1. Which is an example of an object at rest? a. a jet flying overhead b. a chair on a floor c. a rabbit jumping d. a ball hit by a bat

b. a chair on a floor

### 2. When will objects at rest not stay at rest? a. when there is no horizontal motion b. when there is no vertical motion c. when there is no friction d. when objects are acted upon by unbalanced forces

d. when objects are acted upon by unbalanced forces

### 3. What happens to your body's motion when the bumper car you're riding in hits a stopped car? a. Your motion stops. b. Your motion continues with less velocity. c. Your motion continues with the same velocity. d. Your motion continues with greater velocity.

c. Your motion continues with the same velocity.

### 4. Why does a desk quickly stop moving after you push it across the floor? a. The natural state of the desk is at rest. b. There is no longer a force acting on the desk. c. A balanced force acts on the desk. d. An unbalanced force acts on the desk.

d. An unbalanced force acts on the desk.

a. friction

### 6. What is Newton's first law sometimes called? a. the law of friction b. the law of unbalanced forces c. the law of acceleration d. the law of inertia

d. the law of inertia

d. inertia

d. inertia

### 9. What kind of thing has less inertia? a. something with a large mass b. something with a small mass c. something that is moving d. something that is not moving

b. something with a small mass

### 10. Why does it take more force to accelerate a full cart than an empty one? a. The full cart has more mass. b. The full cart is harder to steer. c. The empty cart has more mass. d. You run into air resistance.

a. The full cart has more mass.

b. It increases.

### 12. Which of the following is a simple way to describe Newton's third law of motion? a. Acceleration depends on force. b. All forces act in pairs. c. An object at rest remains at rest. d. A moving object remains in motion.

b. All forces act in pairs.

### 13. What would happen if action and reaction forces acted on the same object? a. The object would move forward. b. The object would move backward. c. The result cannot be predicted. d. The object would not move.

d. The object would not move.

### 14. Which of the following statements about forces is NOT true? a. Forces act in pairs. b. An exerted force always has a reaction force. c. A force never acts by itself. d. Some forces act alone.

d. Some forces act alone.

### 15. Which of the following is an example of an action and reaction force pair? a. gravity from the sun and Earth on a falling ball b. the forces between a bat and ball c. air resistance and gravity on a sky diver d. gravity and friction on a sliding desk

b. the forces between a bat and ball

### 16. When you drop a ball, what is the action force on the ball? a. the ball's gravity pulling on Earth b. Earth's gravity pulling on the ball c. friction between the ball and Earth d. your weight

b. Earth's gravity pulling on the ball

### 17. When you drop a ball, what is the reaction force on the Earth? a. the ball's gravity pulling on Earth b. Earth's gravity pulling on the ball c. friction between the ball and Earth d. your weight

a. the ball's gravity pulling on Earth

### Gravity: A Force of Attraction Facts

• 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

### Gravity and Motion Facts

• Gravity is the force that causes all objects on Earth to accelerate downward at
a rate of 9.8 m/s2.
• Air resistance slows the acceleration of falling objects. An object falls at its
terminal velocity when the upward force of air resistance equals the downward
force of gravity.
• An object is in free fall if gravity is the only force acting on it.
• Projectile motion is the curved path that an object follows when thrown or
propelled near the surface of Earth.
• Projectile motion has two components: horizontal motion and vertical motion.
Gravity affects only the vertical motion of projectile motion.
• Gravity provides the centripetal force that keeps objects in orbit.
• Gravity is the force that keeps the solar system together.

### Newton's Laws of Motion Facts

• Newton's first law of motion states that the motion of an object will not change
if the forces on it are balanced.
• Objects at rest will not move unless acted upon by an unbalanced force.
• Objects in motion will continue to move at a constant speed and in a straight
line unless acted upon by an unbalanced force.
• Inertia is the tendency of matter to resist a change in motion. Mass is a measure
of inertia.
• Newton's second law of motion states that the acceleration of an object
depends on the mass of the object and the amount of force applied.
• The greater the mass of an object is, the greater the force needed to achieve the
same acceleration.
• Newton's third law of motion states that whenever one object exerts a force on
a second object, the second object exerts an equal and opposite force on the
first object.

Example: