The combination of all forces is called the ______.

The combination of all forces is called the __net force__.

In an unbalanced force all forces acting on an object are not _______.

In an unbalanced force all forces acting on an object are not __equal__.

A _______ is a push or pull.

A *force* is a push or pull.

the strength of a force is measure in the SI unit called the ________.

the strength of a force is measure in the SI unit called the __newton (N)__.

What are the 2 types of forces?

1. balanced

2. unbalanced

The Newton was named after the scientist ________.

The Newton was named after the scientist *Isaac Newton*.

Motion does not occur when there is a ______ force.

Motion does not occur when there is a *balanced* force.

In a balanced force, all forces acting on an object are ______ and cancel each other out.

In a balanced force, all forces acting on an object are **equal** and cancel each other out.

Motion occurs when there is an _______ force.

Motion occurs when there is an *unbalanced* force.

A _______ is described by its strength and by the direction which it acts.

A *force* is described by its strength and by the direction which it acts.

Name the 4 types of friction.

1. rolling

2. liquid

3. sliding

4. static

_________ is the force that pulls objects toward each other.

*Gravity* is the force that pulls objects toward each other.

The force that two surfaces exert on each other when they rub together with each other is called _______.

The force that two surfaces exert on each other when they rub together with each other is called *friction*.

Gravitational force depends on the ________ between objects.

Gravitational force depends on the *distance* between objects.

Name the two factors that affect the force of friction.

1. types of surfaces

2. how hard the surfaces are rubbed together

Friction acts in a direction _______ to the direction of the object's motion

Friction acts in a direction *opposite* to the direction of the object's motion

_______ friction occurs between objects that aren't moving.

*Static* friction occurs between objects that aren't moving.

The law of _________ states that the force of gravity acts between all objects in the universe that have mass.

The law of *Universal Gravity* states that the force of gravity acts between all objects in the universe that have mass.

What is an example of fluid friction?

a fish swimming in water

The more mass an object has, the greater its _________ force.

The more mass an object has, the greater its *gravitational* force.

Name the two factors that affect the gravitational attraction between objects.

1. mass

2. distance

________ friction occurs when a solid object moves through a fluid.

*Fluid* friction occurs when a solid object moves through a fluid.

______ friction occurs when 2 solid objects slide over each other.

*Sliding* friction occurs when 2 solid objects slide over each other.

Gravity is a force that pulls objects _______ down toward the center of Earth.

Gravity is a force that pulls objects *straight* down toward the center of Earth.

________ friction occurs when an object rolls across a surface.

*Rolling* friction occurs when an object rolls across a surface.

Newton's 1st law of motion states that rest will remain at rest unless acted upon by a nonzero ________.

Newton's 1st law of motion states that rest will remain at rest unless acted upon by a nonzero *net force*.

Newton's 2nd law states that an object's _______ depends on its mass and on the net force action on it.

Newton's 2nd law states that an object's *acceleration* depends on its mass and on the net force action on it.

Newton's 3rd law states that if one object exerts a _______ on another object, then the second object exerts a force of equal strength in the opposite direction on the first object.

Newton's 3rd law states that if one object exerts a *force* on another object, then the second object exerts a force of equal strength in the opposite direction on the first object.

Resistance to change in ______ is called inertia.

Resistance to change in *motion* is called inertia.

If an object is not moving, it will not start moving unless a _______ acts on it.

If an object is not moving, it will not start moving unless a *force* acts on it.

Newton's 1st law of motion is also called the __________.

Newton's 1st law of motion is also called the *law of inertia*.

Inertia depends on _______.

Inertia depends on *mass*.

The greater the mass of an object, the greater the _______.

The greater the mass of an object, the greater the *inertia*.

If an object is moving, it will continue to move unless a force acts on it to change its ___________.

If an object is moving, it will continue to move unless a force acts on it to change its **speed or direction**.

What formula can we use to find the force of an object?

force = mass x acceleration

For every action, there is an _________.

For every action, there is an **equal but opposite reaction**.

When a car you are in stops suddenly, you move ________ because of inertia.

When a car you are in stops suddenly, you move *forward* because of inertia.

When you walk you push ________ on the ground with your feet, the Earth pushes up on your feet with the same force.

When you walk you push *backward* on the ground with your feet, the Earth pushes up on your feet with the same force.

What law makes this happen: When you walk you push backward on the ground with your feet, the Earth pushes up on your feet with the same force.

Newton's 3rd law

What object would accelerate faster, an empty or full shopping cart?

empty shopping cart

If a car is going 70 mph, how fast is the person in the car going?

70 mph