Question

A particle is projected at an angle of 45 from a point lying 8m from the foot of a wall. It just touches the top of the wall and falls on the ground 4m from it. What is the height of the wall?

Answer 1

Final Answer : 8/3m
Take g = 10m/s^2
Steps :
1) Range = 8+4 = 12m
u^2 sin( 2*45° )/g = 12m
=> u = √120 m/s

2) Find time taken to reach wall by horizontal distance.
After calc, it comes out to be 4/√15 s.

3) Find value of y in that time.
After calculation, y = 8/3 m

For Calculation see pic