Acceleration Acceleration Acceleration is a CHANGE in motion

Acceleration

Acceleration • Acceleration is a CHANGE in motion • An object is accelerating if it is: – Speeding up – Slowing down – Changing direction

Using an Accelerometer • An accelerometer measures acceleration. • CAREFULLY push your accelerometer so it slides across the table and comes to rest. • How does the paper clip show acceleration? • In your notebook, complete the chart for each situation.

Taking a ride on the school bus… • YOU act like an accelerometer when you ride the school bus. • What happens to you, when the bus: – – Speeds up suddenly Turns a corner Stops quickly at a red light Rides along at a steady speed

Taking a ride on the school bus… • When your MOTION CHANGES, that’s a sign that the bus is ACCELERATING.

Is it accelerating? • Your car speeds up when the light turns green. • A racecar goes at a constant speed around a curved track. • A toy car moves in a straight line across the room at a steady speed of 0. 5 m/s. • A roller coaster car slows down as it climbs a hill.

Graphing Acceleration • On a position-time graph, changes in speed are shown by curved lines. Straight line – Not accelerating! Curving up – Speeding up Curving down – Slowing down

• Look carefully at each car below. • Decide which car matches graphs A, B, and C. Graph B – Constant Speed Graph C – Accelerating Slowly Graph A – Accelerating Quickly

Calculating Acceleration • Acceleration is the change in speed per unit of time. Final speed – Initial Speed Acceleration = Time • Acceleration is measured in units of meters per second, or m/s 2.

Calculating Acceleration • A car leaving traffic changed its speed from 10 m/s to 25 m/s in 7. 5 seconds. What was its acceleration? Final speed – Initial Speed Acceleration = Time 25 m/s – 10 m/s Acceleration = = 2. 0 m/s 2 7. 5 s