1. V ELOCITY AND A CCELERATION Let’s Speed Things Up!

2. W HAT IS V ELOCITY ? The velocity of an object tells you both its speed and its direction of motion. A velocity can be positive or negative. The positive or negative sign for velocity is based on the calculation of a change in position.

3. W HAT IS VELOCITY ? Two cars going opposite directions have the same speed, but their velocities are different—one is positive and the other is negative.

4. V ELOCITY E QUATIONS Velocity (v) is calculated by dividing the change in position (Δx) by the change in time (Δt).

5. E XAMPLE OF A V ELOCITY P ROBLEM A car moving north in a straight line at constant velocity starts at a position of 10 meters and finishes at 30 meters in five seconds. What is the velocity of the car?

6. W HAT IS ACCELERATION ? Acceleration – the rate at which velocity changes Can be an: Increase in speed Decrease in speed Change in direction

7. T YPES OF ACCELERATION Increasing speed Example: Car speeds up at green light Decreasing speed Example: Car slows down at stop light Changing Direction Example: Car takes turn (can be at constant speed)

8. F ORMULA FOR ACCELERATION Units for Acceleration = m/s 2

9. A CCELERATION PROBLEMS 1. A skydiver accelerates from 22 m/s to 45 m/s in 2.0 seconds. What is the skydiver’s average acceleration?

10. A NOTHER E XAMPLE : 2. Calculate the acceleration of a car that slows from 55 m/sec to 38 m/sec in 9.6 seconds?

11. A NOTHER EXAMPLE 3. A babysitter pushing a stroller starts from rest and accelerates at a rate of 0.500m/s 2. What is the velocity of the stroller after it has traveled for 0.475 minutes?