Velocity Vectors Bellringer

1. Velocity Vectors Bellringer On your way home from school you encounter a strong wind blowing in the opposite direction that you are biking. The wind is blowing 5 km/hr east and you are biking 18 km/hr west. What is your final velocity? Final Velocity = 18 km/hr west - 5 km/hr east Final Velocity = 13 km/hr west 5 km/hr east 18 km/hr west 1. Draw arrows to represent the directions of the two moving objects. 2. Write the velocity (speed and direction) next to the arrows. 3. Add or subtract the velocities depending on which direction that they are both moving. Include speed, units, and direction!

2. Acceleration • Watch the speed on the odometer in the video clip. This is acceleration! http://www.youtube.com/watch?v=tqvkNDx6JwM • Background information: • 280 km/hr = 174 mi/hr

3. Acceleration Acceleration – the rate of change in velocity Formula: acceleration = final velocity – initial velocity time a = acceleration a = fv – iv fv = final velocity t iv = initial velocity t = time Final units - distance/time/time

4. Where do you find acceleration? Walking Cars picking up speed Anytime you have a change in velocity!

5. Deceleration – negative acceleration Cars stopping or slowing down Balls rising and falling

6. Roller Coasters and Acceleration Position “A” V = 10 m/s Position “C” V = 11 m/s _2_ sec _3_ sec V = 26 m/s Position “B”

7. Practice Problems 1. What is the acceleration between Position “A” and Position “B”? A = fv-iv t A = 26 m/s – 10 m/s 2 s A = 16 m/s 2 s • Draw the equation triangle. • Write the equation. • Substitute your values into the equation (with units!) • Write your final answer with units. A = 8 m/s/s

8. Practice Problems 2. What is the deceleration between Position “B” and Position “C”? A = fv-iv t A = 11 m/s – 26 m/s 3 s A = -15 m/s 3 s • Draw the equation triangle. • Write the equation. • Substitute your values into the equation (with units!) • Write your final answer with units. A = -5 m/s/s