Forces & Motion Notes

Lesson 2: The Force of Gravity

Lesson 3: The Force of A Rubber Band (Elastic Force)

Lesson 4: The Force of Friction

Lesson 2: The Force of Gravity

Matter-

anything that has mass & takes up space

Mass-

the amount of matter in an object

Weight-

the measure of the force of gravity

acting on an object

GravityGravity is a force that pulls objects toward each

other

The force of gravity acts between all objects on earth and in the universe

Earth’s gravity pulls everything towards its center

Forces are measured in Newtons

• The weight of an apple is about 1 Newton.

• The weight of a bag of sugar is 10 Newtons.

Lesson 3:The Force of A Rubber Band

(Elastic Force)

8

Stetching

Pull

Pull harder

hold

hold

9

Stop pulling and ---

• Elastic materials spring back into shape.

• Plastic materials stay stretched.

Elastic Forces

• A type of matter is considered to be elastic if returns to its original shape after being squeezed or stretched.

• Examples of Elastic Matter:• • •

Types of Elastic ForcesThere are two types of elastic forces: tension and compression

Tension Compression

Placing a stent in an artery

1. The squeezed stent is placed at the blockage.2. A balloon opens the stent.3. The stent keeps the artery open so the blood can flow.

Step 1

Step 2

Step 3

Forces can do amazing things!Science saves lives

Lesson 4:The Force of Friction

Friction• Friction is a force that two surfaces exert on each other when

they rub against each other.

• Friction is a force that acts in the opposite direction to the motion of an object.

Types of Friction

Sliding Friction 2 solid surfaces slide over each other

Rolling Friction An object rolls across a surface

Fluid Friction Solid object moves through a fluid

Static Friction Acts on objects that are not moving

Drag= another word for air friction

THE ENDTHE END