A 50.4-g golf ball is driven from the tee with an initial speed of 45.7 m/s and rises to a height of 26.9 m. (a) Neglect air resistance and determine the kinetic energy of the ball at its highest point. (b) What is its speed when it is 7.80 m below its highest point?
(a)at h=0, PE=0, KE = .504*45.7^2/2
at h=26.9, PE=.504*9.8*26.9
the rest is still KE
(b) h=26.9-7.8
figure PE there, solve for v knowing the residual KE.