Coordinated Science C

1. Coordinated Science C Monday, November 26th, 2012 Acceleration and Speed vs. Velocity

2. Entry Task • At this point on the rollercoaster ride, the monks feel like they don’t weigh anything (similar to a sky diver’s free-fall sensation.) • Why do the monks feel like they have no weight when going downhill on the rollercoaster?

3. Students Ideas about Entry Task: • Feel weightless, you feel zero G’s (hangtime). • G-amount of gravitational force. • When you go down you get less G’s. • When you are going down a hill, you are going really fast.

4. Classwork: Rollercoaster’s change in velocity

5. What is the acceleration due to gravity? • -9.8 m/s2 (Why does the acceleration due to gravity have a negative sign?) • Any objects that are close to earth are pulled towards the earth at 9.8 m/s2by the force of gravity. • Physicists are still debating what causes the force of gravity, besides knowing that objects that have mass usually have a gravitational force between them.

6. When does the acceleration of the rollercoaster equal the acceleration due to gravity, but has the opposite sign? Look at your table. • 6 seconds. Why is it not equal and have the opposite sign at 12 seconds? • How do you think you would feel when the acceleration of the rollercoaster equals the acceleration due to gravity? • The weightless feeling discussed in the Entry Task.

7. Design a rollercoaster that gives riders the feeling of weightlessness.

8. Rules for designing rollercoaster When going uphill at the beginning of the ride, you will accelerate. When going uphill any other point, you must decelerate. When going downhill, you should accelerate. Draw two graphs, one showing velocity vs. time and one showing acceleration vs. time. 5. The velocity will always be positive, because the rollercoaster will never be going in reverse. It only goes from the start towards the end.

9. Homework for Tonight: Page. 68 in your Active Physics Textbook: Physics To Go Questions: 1, 3-7