A particle is projected at600  to the horizontal with an energy E. The kinetic energy and potential energy at the highest point are

Initial K.E., E=12mu2 At the highest point, velocity υ= u cos 600=u2 ∴   K.E. at highest point=12mυ2=12m(u2)2                                           =14(12mu2)=E4 PE at highest point =mg×u2sin26002g                                   =12mu2(3 /2)2=34E .