1. RS U2C2A4 Elastic Interactions

2. We Think p 168 Answer #s 1-2

3. Explore Your Ideas Step 1: watch video Step 2: Answer questions 1 & 2

4. 1.What is the evidence that an elastic interaction has occurred? Change in: 1.motion- the ball slows down 2.shape- the ball compresses 3.shape- the strings stretch

5. 2. What is the evidence that an elastic interaction has occurred? Change in: 1.motion- the ball speeds up 2.shape- the ball goes back to its original shape 3.shape- the strings go back to their original shape

6. Make Sense of Your Ideas Read p 169 - Stored Energy AND complete #s 1 - 3 on page 170 You have 5 minutes

7. 1. motion stored elastic 2. Why is the ball included as a receiver in the previous energy diagram? The ball is stretchy and also changes shape when it collides with the racquet.

8. ball stored elastic motion racquet & ball 3. ball leaving racquet

9. Explore Your Ideas Read bottom of page 170

10. the distance the block travels the distance the rubber band is stretched distance the rubber band is stretched distance the block travels more energy will be transferred to the block from the rubber band.

11. Read page 171, then complete Steps 1 - 4

12. object launched rubber band type initial stretch of rubber band We will use the same object each trial We will use the same rubber band for each trial We will use the same chair each trialand will not reposition We will use the same chair each trial and will not reposition

13. (MV) Distance Rubber Band is Stretched 5 cm 10 cm 15 cm 10 12 12 10 22 24 20 22 30 32 32 30 10+12+12+10= 44 44/4= 11 22+24+20+22 =88 88/4= 22 30+32+32+30 =124 124/4= 31

14. the distance the rubber band is stretched the distance the block travels

15. page 623 A valid conclusion: 1.Talks about all the data 2.No opinions

16. (MV) Distance Rubber Band is Stretched 5 cm 10 cm 15 cm If your conclusion is NOT valid, please fix it now!

17. 2. How does your conclusion compare with your hypothesis?

18. 3. Draw an energy diagram to describe the interaction between the rubber band and the block rubber band block decrease in stored elastic energy increase in motion energy Elastic Interaction

19. 4. From your exploration, what evidence do you have to support the claim that energy can be stored in an elastic object?

20. When released, the elastic object transfers energy to the receiver. The block speeds up and the rubber band returns to its original shape

21. Consensus Ideas There are 2 types of elastic interactions: 1. The source transfers mechanical energy to the receiver(s). The source decreases in motion energy. The receiver(s) increase in stored elastic energy.

22. 2. The source(s) transfer mechanical energy to the receiver. The source(s) decrease in stored elastic energy. The receiver increases in motion energy.