Question

a projectile is fired with speed 'u' making an angle from the surface of earth. prove that the projectile will hit the ground of earth with same speed and the same angle

Answer 1

let any projectile fire with u velocity and inclination @ angle with horizontal.
T is time of flight .
after T time body covered displacement in x-axis R and y-axis zero.
now,
Y=UyT -1/2gT^2
0 =usin@T-1/2gT^2

T = 2usin@/g

velocity vector after time t
={ucos@ i + (usin@ -gt) j

tanß =(usin@-gt)/ucos@
where ß is direction of velocity after time t.
now,
put t =T

tanß =(usin@-2usin@)/ucos@
= - tan@
=tan(-@)
hence,
ß = -@
it means magnitude of angle is same but direction is just opposite to each other .
now,
velocity after T time
= ucos@ i - usin@ j

magnitude of V =√u^2(cos^2@+sin^2@)
=u
hence ,
initial speed and velocity with which hit the ground is same .

Answer 2

Answer:

here is ur ans....

Explanation:

hope it helps