Changing Velocity

Constant velocity vs.

Changing velocity

• Velocity is either constant or changing.

• To be constant, the magnitude and the direction can not change.

Constant velocity vs.

Changing velocity

• We have a changing velocity if ANY of the following change

• Magnitude of the velocity

• Direction of the velocity

Try It!• If Kareem Cheese drives his car at 120 km/h north and then turns around to go 120 km/h south, does he have a constant velocity?

• Are his speeds on his north bound and south bound trip the same?

Acceleration• Any time we change speed or direction, we have a change in velocity.

• The measurement of this change in velocity is called acceleration.

• Is acceleration a scalar or vector quantity?

TRY IT!

• Hal Apenyo races his car from a stand still to 50m/s. He does this in 4.20 seconds. What is his acceleration?

• 11.90 m/s/s

Try it!

• How long will it take Pete Abred to get his car from a stand still to 75 m/s if his acceleration is 20m/s/s?

• 3.75 seconds

Acceleration in Action!

• Watch the video and think about when and why there are changes in motion, velocity, and acceleration.

• Bugatti Veyron vs Typhoon Jet