Predict/Explain (a) Referring to the hanging planter in Example 65, which of the three graphs (A, B, or C) in Figure 626 shows an accurate plot of the tensions and as a function of the angle ? (b) Choose the best explanation from among the following: I. The two tensions must be equal at some angle between and . II. is greater than at all angles, and is equal to mg at . III. is less than at all angles, and is equal to 0 at u = 90.

**Workischangeintotalenergyamount. **Kindsofenergycanchangeevenifnoworkisdone. • GravitationalPotentialEnergy o Lifting/loweringthings;“height” o U =Gmgh § U G=(mass)(gravity)(height) § Example:Massof60kgliftedfromheight3mà4m.Beforeand afterGPE,howmuchwork 2 U Gi(60kg)(9.8m/s )(3m)=1764J 2 U Gf(60kg)(9.8m/s )(4m)=2352J W=U GfU =Gi88J • KineticEnergy“motion” 2 o K=½mv Example:Howmuchenergydoesa0.25kgballhaveat5m/s K=½mv =½(0.25kg)(5m/s) 2