# Measuring Motion

## Speed

• Definition: Distance traveled by an object divided by the time taken to travel that distance.
• Measured in meters per second(m/s)
• Formula for speed: S=d/t
• Since objects don't usually travel at a constant speed you typically just give average speed.

## Velocity

• Definition: speed of an object in a specific direction.
• The formula for velocity is v=d/t.
• An object's velocity is constant if the direction or speed doesn't change.
• The velocity will change if the direction or speed changes.
• There is also resultant velocity- the combined velocity of different objects in motion.
• Speed and velocity are NOT the same.

## Acceleration

• Definition: A measure of how much the velocity changes in a certain amount of time.
• An object accelerates if its direction,speed, or both change.
• There is positive acceleration (increase in velocity) and negative acceleration (decrease in in velocity.)
• The faster the change in velocity is, the great acceleration there is.

## Work

• Definition: When a force causes an object to move in the direction that force is applied over a distance(or force) that stops the movement.
• The formulas for work is W=Fd.
• Work is measured in joules(J).
• If there is no movement over a distance the is no work.
• There is positive work- when motion and force are in the same direction and negative work- when motion and force are in opposite directions.