A tennis ball projected at an angle 0 attains a range R = 78. If the velocity imparted to the ball by the racket is 30 ms(^{-1}), calculate O. [ g = 10 ms(^{-2})]
Explanation
R = (frac{U^2 sin 2theta}{g}), 78 = (frac{30^2 sin 2theta}{10})
(sin2theta = frac{780}{900}) = 0.8667, (2theta = sin^{-1}0.8667 = 60^o)
(theta frac{60^o}{2} = 30^o)