Figure 10-19 is a graph of the angular velocity versus time for a disk rotating like a merry-go-round. For a point on the disk rim, rank the instants a, b, c, and d according to the magnitude of the (a) tangential and (b) radial acceleration, greatest first.

**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