A stone is thrown from the top of a tower at an angle 30 degree up with horizontal with velocity - Physics - Motion In A Plane

Question

A stone is thrown from the top of a tower at an angle 30 degree
up with horizontal with velocity of 16 m/s After 4 seconds of
flight it strikes ground Calculate height of tower from ground

Panchali Dutta · Accepted Answer

Initial velocity, u = 16m/s

Total time taken, t = 4s

Maximum height reached by the stone be h m.

$v^{2} - u^{2} si n^{2} θ = - 2 g h \Rightarrow h = \frac{u^{2} si n^{2} 30}{2 g} = 3.2 m$

Time required to reach this height be t's

$v = u \sin 30 - g t' \Rightarrow t' = \frac{u \sin 30}{g} = 0.8 s$

Time taken from the maximum height to reach the ground, T = t - t' = 3.2s

Let the height of the tower be H m.

$H + 3.2 = 8 T + \frac{1}{2} g T^{2} = 76.8 \Rightarrow H = 73.6 m$

A stone is thrown from the top of a tower at an angle 30 degree up with horizontal with velocity of 16 m/s.After 4 seconds of flight it strikes ground.Calculate height of tower from ground.