Question

a ball is projected from ground at an angle 45 degree with horizontal from distance d1 from the foot of a pole and just after touching the top of pole it the falls on ground at the distance d2 from pole on other side the height of pole is

Answer 1

Answer:

d1 * d2 / [ d1 + d2 ].

Explanation:

We will get the horizontal component to be  as x = u cosФ*t = u t/√2 since the value of the Ф is = π/4 and, the distance  y = u sinФ  t - 1/2 g  t^2 will be equal to =  u/√2 - 1/2 g t^2

 

Again we know that the y = x  - g x^2 / u^2  since the value of the tanФ = 1  and cosФ =1/√2.

If we take x = d1,  y = h to be the height of the pole.

h = d1 - g d1^2 / u^2 ....(1)

Now from the question, when  x = d1 + d2 and the value of y = 0.

Hence,  0 = (d1+d2) - g (d1 + d2)^2/u^2.  

u^2 = g (d1 + d2)  ...(2)

Now if we substitute the equation (2) in (1) we will get:

h = d1 - d1^2/(d1+d2) = d1 * d2  / (d1 + d2).

So on solving we will get the value as  d1 * d2 / [ d1 + d2 ].

Answer 2

Explanation: hope it helps you