A ball is fired at a speed of 8 ms at 20 above the horizonta

A ball is fired at a speed of 8 m/s at 20 above the horizontal from the top of a 5 m high wall. What is the total velocity at the maximum height? (number expressed with one decimal place).

Solution

ball is fired at a speed of 8 m/s at 20^o above horizontal

==> horizontal component of velocity of ball u_x = 8cos(20^o)

==> vertical component of velocity of ball = u_y = -9.8t + 8sin(20^o)

At maximum height vertical component of velocity is zero , only horizontal component exists .

horizontal component of velocity is always constance since there is no acceleration in horizontal direction.

Hence velocity at maximim height = 8 cos(20^o) = 8(0.9397) = 7.517

Hence velocity at maximim height = 7.5 m/s