# Forces and Motion

### 28 terms by Princess-Savvy

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### displacement

the direction and the distance between the final position and the starting position

### speed

the distance traveled divided by the time needed to travel that distance ( s = d/t )

### velocity

the speed in a particular direction

### acceleration

a change in velocity divided by the amount of time over which the change occurs ( a = F/m )

### force

a push or a pull ( F = ma )

### inertia

measures an object's tendency to resist a change in motion

### balanced forces

forces that cancel eachother out ( they do not cause a change in motion )

### unbalanced forces

forces that are not balanced; they do cause a change in motion ( the object will move in the direction of the stronger force )

### friction

resists motion between two touching surfaces

### gravity

a pull that all matter exerts on other matter

### centrifugal force

causes the object to move away from the center

### centripetal force

causes the object to move in a circular path towards the center

### Newton's First Law of Motion

an object at rest tends to stay at rest, an an object in motion keeps moving in a straight line at constant speed until an outside force ( or unbalanced force ) stops it

### Newton's Second Law of Motion

acceleration depends on the mass of an object and the force pushing or pulling the object

### Newton's Third Law of Motion

for every action, there is an equal and opposite reaction that happens at the same time

### Newton's First Law of Motion example

If a ball is not moving, it will stay that way until some force makes make it move.

### Newton's Second Law of Motion example

If two bike riders pedal with the same force, the rider moving less mass accelerates fatser.

### Newton's Third Law of Motion example

A girl jumps on a trampoline. The action is the girl pushing down on the trampoline. The reaction is the trampoline pushing up on her.

### balanced force example

A boy is pushing up against a cement wall. No matter how hard he tries, the wall will not move.

### unbalanced force example

A towtruck towes a car after a wreck. As a result, the car is moving in the direction of the towtruck.

### centrifugal force example

A person rides the merry-go-round.

### centripetal force example

The moon orbits Earth.

### velocity example

A car is traveling 30 mph/south.

### speed example

The long distance jogger's time was 6 mph for the race.

### acceleration example

A softball is hit into the outfield.

### acceleration formula

a= F/m or fV - iV/t

F = ma

m= F/a

Example: