1. Velocity and Acceleration

2. Velocity
= speed in a direction! Examples: 5 m/s up 12 mph north 1,425 k/h south southwest

3. Velocity
To compute first figure average speed. S= d/t Then add the direction!

4. Combining velocities
You are on an escalator that goes up 1 m/s. So you decide to walk up 1.7 m/s. Since it is going in the same direction, you can add the speeds (1 m/s m/s) and you’re velocity is 2.7 m/s up!

5. ?????
Think and Share When else might you combine velocities going in the same direction? Hint: Ever been to the Atlanta airport?

6. Combining Velocities in different directions
But what if you were going different directions and traveling down the up escalator? How can we figure your velocity?

7. Combining conflicting (different direction) velocities
If the escalator moves 1 m/s up but you’re moving 1.7 m/s down, what’s your velocity?

8. Combining velocities
Easy! If you’re combining opposite velocities you subtract! 1.7 m/s down – 1.0 m/s up = .7 m/s down It just makes sense!

9. Acceleration
Acceleration is any change in velocity. Since velocity is speed in a direction, you can accelerate by:
Increasing speed
2) Decreasing speed (aka deceleration
or negative acceleration) or
3) Changing direction

10. Acceleration
Let’s all accelerate!

11. Examples of Acceleration
A plane taking off increase in speed Jogging on a winding trail change in direction Driving around a corner change in direction Stopping at a stop sign decrease in speed Standing on the equator change in direction Any circular motion change in direction

12. Acceleration Graphs
Graphs of objects accelerating look like this

13. Acceleration Graphs
Graphs of negative acceleration also called deceleration, look like this:

14. Continuous Acceleration
Since something moving in a circle is always changing directions, it is continuously accelerating!