1. 3.3 Hooke’s Law

2. TODAY’s OBJECTIVES To learn about how stretch or compression of a spring varies with gravitational force.

6. x = amount of stretching/compression F = force exerted on an object (F g, F app …)

7. x = amount of stretching/compression F = force exerted on an object (F g, F app …)

8. x = amount of stretching/compression F = force exerted on an object (F g, F app …) k = spring constant

9. Robert Hooke 9 First one to notice this relationship

10. Robert Hooke 10 If too much force is applied and an object is stretched or compressed too much, the direct proportion breaks down!

11. Example 1 11 F app = ?? ∆x = 20 cm = 0.20 m k = 3.2 F app = k · ∆x F app = 3.2 · 0.20 F app = 0.64 N 1.33 N/cm

12. Example 1 12 m = 2.5 kg ∆x = 10 cm = 0.10 m If, m = 5.0 kg ∆x = ??? F g = k · ∆x m · g = k · ∆x 2.5 · 9.8 = k · 0.10 k = 245 N/m F g = 245 · ∆x

13. CLASSWORK Problems: 3.3 Review Problems Page: 97 13

14. HOMEWORK Problems: Chapter 3 Review Questions (# 10) Page: 99 14

15. Chapter 3 TEST Thursday, November 14 15

16. Chapter 3 TEST Problems: Chapter 3 Review Questions (# 1 - 9) Page: 98 - 99 16

17. Laboratory Investigation 3 – 3 Another Way to Weigh 17