# Chapter 4 and 5

## 26 terms

### Aristotle's view of motion

Force causes motion

### Galileo's view of motion

Force changes motion

any push or pull

### Friction

Force between two materials in contact as they move past each other

### Cause of friction

surface irregularities (bumps)

### Newton's First Law

An object in motion stays moving in a straight line at a constant speed and an object at rest stays at rest unless acted on by a net force

Mass

### Mass

the amount of matter in an object

### Volume

the amount of space that an object takes up

### Weight

The force of gravity on an object

### Newton

the unit that measures force (1N = 1 kg.m/s^2)

### Net Force

the combination of all forces that act on an object

### Support Force

An upward force on an object that balances out the force of gravity

### Normal Force

A force that acts perpendicular to the surface of an object

### Equilibrium

When the net force equals 0

acceleration

### Relationship between force and acceleration

Directly proportional

### Relationship between mass and accleration

Inversely proportional

### Newton's Second Law

the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to the mass of the object

### What does the amount of Friction depend upon

The roughness of the surfaces and how hard they are pressed together

### Air Resistance

The friction acting on something moving through air

### Force Diagram

A drawing showing all the forces acting on an object

### Pressure

The amount of force applied over an area

### Pascals

The unit of Pressure (N/m^2)

### What two things does air pressure depend on?

The surface area and speed of the object

### Terminal Velocity

The speed at which a falling object no longer accelerates because the air resistance equals the weight

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