# Newton's Laws and Physics Concepts

## Gravity

Gravity - attractive forces between 2 objects that depends on mass and distance

How it applies - When the ball falls to the ground after being kicked, one of the forces is gravity. Since the ball has a smaller mass, it takes longer to fall the the ground. There is more gravity in objects with larger mass, so the ground has a large amount of gravity, but the ball doesn't.

## Friction

Friction - a force that opposes a sliding object

How it applies - When the ball slides on the grass, the grass opposes it, making the ball slowdown and eventually stop. Grass has more friction than other surfaces, like ice, which causes little friction. Grass causes more friction, and the ball slows down quicker.

## Newton's first law and Inertia

Newton's First Law - an object in motion or at rest tends to stay in motion/rest unless an unbalanced force acts upon it

Inertia - tendency of an object to stay in motion/rest

How they apply - When the ball keeps rolling until someone or friction stops it, Newton's first law and inertia apply. The outside force would be friction or the person's foot. Both of these would stop the ball from staying in motion.

## Newton's Second Law

Newton's Second Law - force equals mass times acceleration

How it applies - Newton's second law applies to how hard you kick the ball. The ball's mass is light, but the acceleration would be large, making the force stronger.

## Newton's Third Law

Newton's Third Law - for every action force, there's an equal and opposite reaction force from the second object onto the first

How it applies - when someone kicks the ball, the ball pushes back. The reaction force isn't as strong as the action force.

## Balanced and Unbalanced Forces

Balanced Forces - Equal and opposite forces

How it applies - When the player stops the ball, there are balanced forces. The ground it pushing up on the ball, and the player's foot is pressing down. The net force is 0, and the ball stops moving.

Unbalanced Forces - When net force doesn't equal zero

How it applies - When the player kicks the ball, there are unbalanced forces. The most powerful force is the player's kick. There is no force stopping the ball completely, until gravity affects it. Gravity is the weaker force. The net force doesn't equal 0, therefore making the forces unbalanced.