 # Acceleration Chapter 3 Section 1.

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Acceleration Chapter 3 Section 1

What is Acceleration? Speed is the rate of change of position.
Galileo defined Acceleration as the rate of change of velocity. What does that mean it has? HINT

Acceleration Hints! Because velocity includes speed and direction of an object, acceleration can be a change in: How fast the object is moving What direction the object is moving Acceleration occurs when an object changes its speed or direction, or both!

Speeding up or Slowing down?
When a car speeds up, that is POSITIVE ACCELERATION! When a car slows down, that is NEGATIVE ACCELERATION or DECELERATION!

Acceleration Formula Acceleration = Change in Velocity/Time A = ΔV/T

Positive Acceleration
A motorcycle starts at rest and accelerates to 80 m/s in 20 seconds A= ΔV/T = 80 m/s/ 20s A= 4 m/s2

Distance vs. Time Graph When Accelerating

Negative Acceleration/Deceleration
A skateboarder moves in a straight line at 3 m/s and comes to a stop in 2 s. A= ΔV/T =– 3 m/s/2s A= -1.5 m/s2

Free Fall When air resistance doesn’t affect the motion of a falling object, we say the object is in free fall. Downward falling objects gain speed because of the force of gravity.

Object thrown Upwards What happens when an object gets thrown upwards?
While going up, it moves against gravity. At the highest point, when it changes direction from upward to downward, its instantaneous speed is zero. Then it starts downward just as if it had been dropped from rest.

Acceleration Acceleration is the rate of change of velocity.
Acceleration = change in velocity time interval Symbol: A Units: m/s2