1. Energy
Spring Force &
Elastic Potential Energy

2. Figure 6.5a

3. Figure 6.5b

4. Figure 6.6

5. The slope of the F vs Δx graph is called the spring constant (k)
The slope of the stiffer spring 2 is larger (33 N/m) than the slope for spring 1 (20 N/m). This means that to stretch spring 1 by 1m, we would only need to exert a 20-N force, but would need a 33-N force for spring 2.

6. Figure 6.7a

7. Figure 6.7b

9. Hooke’s Law
If any object causes a spring to stretch or compress, the spring exerts an elastic force on that object. If the object stretches a spring, the force that the spring exerts is

10. Scenario: A person pulls a spring horizontally to stretch it.

11. How much work did we do to stretch the spring?

12. The amount of work done on the spring is the area under the F-vs-x graph
Positive work done on a spring, through stretching or compressing the spring, transfers elastic potential energy (Us) into the spring

13. The elastic potential energy of a spring-like object with a spring constant k that has been stretch or compressed a distance Δx from equilibrium is
Just like any other type of energy, the unit of elastic potential energy is the joule (J).

14. How fast will the arrow be moving when it leaves the bow?
Shooting an Arrow
How fast will the arrow be moving when it leaves the bow?

16. Human Cannonball WB
What strength of spring should they buy so that they can use the cannon as desired?

18. Bungee Jumping
Unnumbered Figure 4 Page 207

19. Unnumbered Figure Page 208