FORCES

Forceany push or pull Example: opening a door

Pushing something across the floor

Balanced Forces

• Do not cause a change in motion. They are equal in size and opposite in direction. The forces cancel each other out

• Example: When arm wrestling neither arms are moving

• Pushing/Leaning against a person and neither moving

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Unbalanced ForcesAlways cause a change in motion. They are not equal and opposite.

Example: When arm wrestling, one person is stronger and their hand goes down (one person wins)

Pushing against a person and one person moves/falls

FrictionThe force that one surface exerts on another when the two rub against each other

Example: When you roll a ball across the floor, it loses energy as it rolls due to friction

InertiaAn object at rest stays at rest, and an object in motion will stay in motion unless acted on by a force

Example: the ball would continue rolling across the floor if there was no friction (until it hit something that makes it stop)