# Chapter 2-Forces, friction, and gravity

## 47 terms

### What is a force?

a push or pull first exerting force on a second

Net force

### Unbalanced forces can do three things. What are they?

1. Combine
2. Subtract
3. Cancel each other out

Balanced forces.

zero

### What is Newton's First Law of Motion?

An object at rest will remain at rest, and an object that is moving at constant velocity will continue moving at constant velocity unless acted upon by a unbalanced force.

### Newton's First Law of Motion is also called....

The Law of Inertia

### What is mass?

The amount of matter in an object.

### How can mass be defined in terms of inertia?

Mass can be defined as a measure of the intertia of an object.

### What is Newton's Second Law of Motion?

The net force of an object is equal to the product (addition) of its acceleration and mass.

### What is the equation that describes the relationship among quantities of force, mass, and acceleration.

Force=Mass x Acceleration

### What equation for Newton's second law can you use to find accleration?

Accleration=Force divided by Mass.

### How does an increase of force affect acceleration?

An increase of force causes an increase in acceleration.

### What are two ways you can increase the acceleration of an object?

You can change the force and change the mass.

### How does an increase fo mass affect accleration?

An increase of mass decreases acceleration?

### What two factors does friction depend on?

1. The types of surfaces involved
2. How hard the surfaces push together

### What direction does friction go?

Opposite to the object's direction.

Sliding Friction

Gravity

### When is an object said to be in free fall?

When the only force acting upon it is gravity.

9.8 m/s squared

Projectile

### Air Resistance is...

Objects falling through the air (fluid friction).

Air resistance

### What is terminal velocity?

The greatest velocity a falling object reaches

### What is weight?

The force of gravity on an object at the surface of a planet.

### How is weight different than mass?

Weight is the measure of the force of gravity and mass is a measure of the amount of matter in a object.

Newtons

### What does the universal law of gravitation state?

The force of gravity acts between all objects in the universe.

Mass + Distance

### What is Newton's third law of motion?

If one objects exerts a force on another object, then the second object exerts a force of equal magnitude in the opposite direction of the first object.

Action

Reaction

### Forces can only be added together if...

they are acting on the same object

### Momentum is...

The product of an objects mass and velocity is

mass x velocity

kg x m/s

### What of the law of conversation of momentum state?

The total momentum of the objects that interact does not change.

### Momentum is ______, but ________ to the other object.

conserved, transfered

### What is Newtons 2nd law of motion?

the net force on an object is the product of its acceleration and its mass.

### What is Newtons 1st law of motion?

an object at rest will remain at rest and an object in motion will remain in motion unless the object is acted upon by an unbalanced force.

### What is newtons 3rd law of motion?

everytime there is an action force on an object the object will exert an equal and opposite reaction force.

### Do action/reaction forces cancel out?

No because they are acting on two different objects.

### What does momentum count on?

a greater mass or velocity

one increases

### Momentum: One moving object

Transfered from one to another

### Two connected objects

Velocity divided in half