Question

A ball is thrown vertically upwards with a velocity of $19.6 ms^{–1}$ from the top of a tower. The ball strikes the ground after $6 s$. The height from the ground up to which the ball can rise will be $(k/5) m$. The value of k is ______ (use $g = 9.8 m/s^2$)

Answer 1

$v = 19.6 m/s$

$t = 6s$

Time taken in upward motion above tower = $2s$

⇒ Time taken from top most point to ground = $4s$

⇒ $\sqrt{\frac{2h}{g}}=4$

$h=\frac{16×9.8}{2}=8×9.8$

⇒ $k=8×9.8×5=392$