Motion and forces

Motion

The change in the position of an object

Frame of reference or the reference point

The object a person uses to detect motion

Measuring motion or calculating speed

Speed equals distance divided by time S equals Distance over time

Speedometer

A device that shows the instantaneous speed

Velocity

The speed and direction of an object

Example. 100 ft./s north.

Acceleration

Any change in velocity, which is any change in speed or direction

Three ways

Speed up, slow down or turn

What is a force?

A push or a pull on an object

Net force

A combination of all forces acting on an object

Balanced force

Equal and opposite forces example 15 and left 15 and right net force would be zero cause they cancel out

Unbalanced force

Needed to create motion or change motion example. 15 and left 13 and right net force two and left

Friction

A force created by two surfaces that are touching

Two effects of friction

Slow motion and creates heat

Helpful friction

Writing walking and driving

Harmful friction

Erosion Machines being worn out

Lubricant

A substance that reduces friction such as oil lotion or grease

Air resistance

Friction between one surface and the air

Mass

The amount of matter and an object mass always stays the same. It does not change when your location changes.

Gravity

The force of attraction between any two objects

Universal law of gravitation

As mass increases, the force of gravity increases

As distance increases, the force of gravity decreases