A stone is projected at angle 30° to the horizontal. The ratio of kinetic energy of the stone at point of projection to its kinetic energy at the highest point of flight will be:
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A stone is projected at angle 30° to the horizontal. The ratio of kinetic energy of the stone at point of projection to its kinetic energy at the highest point of flight will be:

G1 Physics · Accepted Answer

At projection, KE = (1/2) μ \mu μ ². At the highest point, only horizontal speed u cos30° remains, so KE(top) = (1/2)m(u cos30°)². Therefore KE(projected)/KE(top) = 1/cos²30° = 4/3.