Ap World Ch 4

Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object.

Always true

A force can be simply defined as a push or a pull.

True

A rocketship is pushed forward by gases that are forced out the back of the ship.

True

An astronaut has the same mass on Earth as in space.

True

Friction refers to the force between two surfaces that are sliding past each other.

True

Inertia is the property that every material object has; inertia resists changes in an object's state of motion.

True

The net force on an objecting falling at terminal velocity is zero.

True

Whenever one object exerts a force on another object, the second object always exerts a force back on the first object.

True

The acceleration of an object is inversely proportional to the net force acting on it.

false

The speed of an object dropped in air will continue to increase without limit.

false

Accelerations are produced by

forces

According to Newton's third law, if you push gently on something, it will push

gently on you

An object following a straight-line path at constant speed

has zero acceleration.

Forces always occur

in pairs

One object has twice as much mass as another object. The first object also has twice as much

inertia

How does acceleration of an object change in relation to its mass? It is

inversely proportional

A karate chop delivers a blow of 2300 N to a board that breaks. The force that acts on the hand during this feat

is 2300 N

An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is

larger

Compared to its weight on Earth, a 10-kg object on the moon will weigh

less

A rocket is able to accelerate in the vacuum of space when it fires its engines. The force that propels the rocket is the force

of the exhaust gases on the rocket

A high school student hits a nail with a hammer. During the collision, there is a force

on the nail and also on the hammer

Friction is a force that always acts

opposite to an object's motion

A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the

road

The reason a tennis ball and a solid steel ball will accelerate at the same rate, in the absence of air resistance, is that

the ball with the larger force also has the larger mass

A heavy person and a light person parachute together and wear the same size parachutes. Assuming they open their parachutes at the same time, which person reaches the ground first?

the heavy person

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that

the milk carton has inertia.

An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is

the same

Compared to its mass on Earth, the mass of a 10-kg object on the moon is

the same

A large truck and a small car traveling at the same speed have a head-on collision. The vehicle to undergo the greater change in velocity will be

the small car

A push on a 1-kilogram brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kilogram brick, one would have to push

with 10 times as much force

The force required to maintain an object at a constant speed in free space is equal to

zero

After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals

zero, since no force is necessary to keep it moving.

An apple weighs 1 N. The net force on the apple when it is in free fall is

1N

As a 600-N woman sits on the floor, the floor exerts a force on her of

600 N

A sportscar has a mass of 1500 kg and accelerates at 5 meters per second squared. What is the magnitude of the force acting on the sportscar?

7500 N.

How much force is needed to accelerate a 4.0-kg physics book to an acceleration of 2.0 m/s2?

8.0 N

If the force acting on a cart doubles, what happens to the cart's acceleration?

It doubles

Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?

It halves

Which has more mass, a kilogram of feathers or a kilogram of iron?

Neither-they both have the same mass

A girl pulls on a 10-kg wagon with a constant force of 20 N. What is the wagon's acceleration?

2 m/s2

A tow truck exerts a force of 2000 N on a car, accelerating it at 1 m/s/s. What is the mass of the car?

2000 kg

Suppose the force of friction on a sliding object is 25 N. The force needed to maintain a constant velocity is

25 N

Two people pull on a rope in a tug-of-war. Each pulls with 400 N of force. What is the tension in the rope?

400 N

A jumbo jet cruises at a constant velocity when the total thrust of the engines on the jet is 50,000 N. How much air resistance acts on the jet?

50,000 N

A woman weighing 550 N sits on the floor. She exerts a force on the floor of

550 N

A 6-N falling object encounters 6 N of air resistance. The magnitude of the net force on the object is

0 N

A book weighs 4 N. When held at rest in your hands, the net force on the book is

0 N

When an object reaches terminal velocity its acceleration is

0 m/s2.

A 20-N falling object encounters 4 N of air resistance. The magnitude of the net force on the object is

16 N

In order to make a cart move forward, a horse must pull harder on the cart than the cart pulls on the horse.

'False

The combination of all the forces that act on an object is called the net force.

'True'

If shopping cart A has five times more mass in it than shopping cart B and the two carts are pushed with equal forces, you can expect the acceleration of shopping cart A to be

1/5 times that of shopping cart B.

A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is

10 times as much as the force on the 1-kg book.

A box is dragged without acceleration in a straight-line path across a level surface by a force of 13 N. What is the frictional force between the box and the surface?

13 N

A bicycle and a parked car have a head-on collision. The force of impact is greater on the bicycle.

False

A given force exerted on a large mass produces a greater acceleration than the same force exerted on a small mass.

False

An astronaut weighs the same on Earth as in space.

False

If a hockey puck were to slide on a perfectly frictionless surface, it will eventually slow down because of its inertia.

False

If you were to slide a hockey puck across a frictionless ice rink, there must be a horizontal force on it to keep it in motion.

False

The SI unit of mass is the newton.

False

The amount of matter in an object is its weight.

False

The force due to gravity acting on an object is its mass.

False

A player hits a ball with a bat. The action force is the impact of the bat against the ball. What is the reaction to this force?

The force of the ball against the bat

A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. What is the reaction to this force?

The force the glove exerts on the ball

An object weighs 30 N on Earth. A second object weighs 30 N on the moon. Which has the greater mass?

The one on the moon

As a ball falls, the action force is the pull of Earth's mass on the ball. What is the reaction to this force?

The pull of the ball's mass on Earth

A tennis ball and a solid steel ball with the same diameter are dropped at the same time. Which ball has the greater force acting on it?

The steel ball

A tennis ball and a solid steel ball with the same diameter are dropped at the same time. In the absence of air resistance, which ball has the greater acceleration?

They both have the same acceleration.

If a horse pulls on a wagon at rest, the wagon pulls back equally on the horse. Can the wagon be set into motion?

Yes, because there is a net force acting on the wagon.

The acceleration produced by a net force on an object is d

a. inversely proportional to the mass of the object. b. directly proportional to the magnitude of the net force. IncorrectIncorrect c. in the same direction as the net force. d. all of the above e. none of the above

The law of inertia states that an object e

a. will continue moving at the same velocity unless an outside force acts on it. b. will continue moving in a straight line unless an outside force acts on it. c. that is not moving will never move unless a force acts on it. d. at rest will remain at rest unless acted on by an outside force. e. will do all of the above.

The law of inertia applies to

both moving and nonmoving objects