Question

From the top of a tall building, a gun is fired. The bullet leaves the gun at a speed of 340 m/s, parallel to the ground. The bullet puts a hole in a window of another building and hits the wall that faces the window. (y = 0.42 m, and x = 7.2 m.)Determine the distances D and H, which locate the point where the gun was fired. Assume that the bullet does not slow down as it passes through the window.

Answer 1

let vy=is vertical componet then t' time of flight
x=ut'
y=vyt'-gt'^2/2
then eliminate the two equation
H= y +gt^2/2
and to find vy
vy=yu/x +gx/2u
D+x=ut
substitute the tow equation,
D=usqrt(2H)/g -x