Question

A balL is thrown with a velocity of 12m/s at an elevation angle of 30 from the
top Of a tower with height 61m. Find the time taken by it to reach the ground. At what distance from the foot of the to were will it hit the ground?

Answer 1

The component of velocity in the vertical-upward direction is,

v=50sin(30

0

)=50×0.5=25m/s

Let the time taken to reach ground from initial position be t sec

The acceleration due to gravity is, g=10m/s

2

, in the vertical-downward direction.

and the distance traveled is, h=70m, in the vertical-downward direction.

So here, h=−vt+

2

1

gt

2

⟹70=−25t+(0.5×10×t

2

)

⟹t

2

−5t−14=0

Solving above quadratic equation, we get t=−2,7

As time is always positive, t=7s