A test

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

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?

400N

Suppose the force of friction on a sliding object is 42 N. The force needed to maintain a constant velocity is

42N

Free-body diagram

A diagram showing all the forces acting on an object

Interaction

A mutual action between one object and another

Netwon's 2nd Law

F=ma

True or False: All forces that are equal and opposite are considered action-reaction pairs.

False

Newton's 3rd Law

For every action there is an equal and opposite reaction

Air resistance

Friction, or drag, that acts on something moving through air

Fluids

Liquids and Gases

A person driving a car crashes into a pole. The effect is the person flies forward. This is an example of

Newtons 1st Law

Pressure

The amount of force applied to a particular area

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

Terminal Speed

The speed at which the acceleration of a falling object is zero

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

Surface Area

both pressure and air resistance depend on this

If you exert 12 N on a 3 kg car and a 6 kg truck that are both originally at rest, what will be the resulting accelerations of the objects?

car at 4 m/s/s; truck at 2 m/s/s

A force of 4 N accelerates a mass of 4 kg at the rate of 1 m/s/s. The acceleration of a mass of 8 kg acted upon by a force of 8 N is

continues at the speed it had when it encountered the force

Pressure is defined as

force per area

Accelerations are produced by

forces

on the nail and also on the hammer

larger

If a truck has ten times the mass of a car and the two vehicles are pushed with an equal force, you would expect the acceleration of the truck to be

1/10 times that of the car

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?

1/2 as much

A sportscar has a mass of 2000 kg and accelerates at 5 m/s². What is the magnitude of the force acting on the sportscar?

10000N

A 20-N falling object encounters 8-N of air resistance. The magnitude of the net force on the object is

12N

An book weighs 15 N. The net force on the book when it is in free fall is

15 N

A boxer punches a bag with 1500 N of force. What force does the bag exert on the boxer's hand?

1500N

When a woman stands on one foot on a scale. The scale reads 295 N. When she puts her other foot down on the scale, the scale reads

295N

A jet has a mass of 40,000 kg. Each engine has a thrust of 20,000 N. There are 6 engines. What is the jet's acceleration when taking off?

3 m/s²

An ATV pulls a 25 kg log with 300 N of force. There is 200 N of friction. What is the acceleration?

4 m/s/s

A girl pulls on a 10-kg wagon with a constant force of 40 N. What is the wagon's acceleration?

4 m/s²

A jumbo jet cruises at a constant velocity when the total thrust of the engines on the jet is 40,000 N. How much air resistance acts on the jet?

40,000N

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

600N

You pull horizontally on a 50-kg crate with a force of 600 N and the friction force on the crate is 250 N. The acceleration of the crate is

7 m/s²

A tow truck exerts a force of 1500 N on a car, accelerating at 2 m/s/s. What is the mass of the car?

750 kg

all of the above are examples of equilibrium

A) in order for the car to move, a force must be exerted by you on the car's windshield B) in order for the car to move, a force must be exerted by the car's windshield on you C) in order for the car to move, an outside force must be exerted on the car D) in order for the car to move, a force must be exerted by the car on the ground

Which of the following does NOT effect air resistance?

Weight

Inversely

When two values change in opposite directions, so that if one increases the other decreases

When an object is in equilibrium it is

all of the above are examples of equilibrium

Nellie Newton holds an apple in her hand. If action is Earth pulling on the apple, then reaction is

apple pulling the earth

You are on a frozen pond, and the ice starts to crack. If you lie down on the ice and begin to crawl, this will

decrease the pressure on the ice

A care package falls from a high-flying stationary helicopter. There is air resistance. The package's velocity increases and its acceleration

decreases

When the angle of an incline with a block resting on it increases, the normal support force

decreases

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

inversely proportional

A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is

its weight

The unit of pressure is

newtons per square meter (or pascals)

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

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

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

road

Which of the following does friction NOT depend on?

surface area

You drive past a farm and you see a cow pulling a plow to till a field. You have just learned about Newton's third law, and you wonder how the cow is able to move forward if the plow is exerting an equal and opposite force on the cow. Which of the following explains the movement of the cow and plow?

the force exerted by the cow on the plow is smaller than the force that the cow exerts on the ground to move forward

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

Why is the bed of nails (relatively) safe?

the nails are close together, increasing surface area

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 the earth

A force of 4 N accelerates a mass of 4 kg at the rate of 1 m/s/s. The acceleration of a mass of 8 kg acted upon by a force of 8 N is

the same

A care package falls from a high-flying stationary helicopter. There is air resistance. The package's velocity increases and its acceleration

the skydiver decelerates, but the camera-man does not

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

triples