Question

A stone is projected upwards at an angle of 30 degree to the horizontal from the top of a tower of height 100m and it hit the ground at a point Q. if the initial velocity of projection is 100m-1. calculate the ; (I) maximum height if the stone above the ground (ii) time it fakes to reach this height (iii) time if flight (iv) horizontal distance from the foot of the tower to the point Q. (Neglect air resistance and take g as 10ms-2)?

Answer 1

Answer:

Explanation: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

Option C is correct.