Figure 24-59 shows a ring of outer radius R = 13.0 cm, inner radius r = 0.200R, and uniform surface charge density if = 6.20 pC/m2. With V = 0 at infinity, find the electric potential at point P on the central axis of the ring, at distance z = 2.00R from the center of the ring.
**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