Question

Two thin wood screens A and B are separated by 200m . A bullet travelling horizontally at a speed of 600m/s hits the screen A ,penetrates through it finally emerges out from B making holes in A and B . If the resistance of air and wood are negligible , the difference of heights of the holes in A and B is

Answer 1

Here the bullet should be considered as a projectile

Initially the bullet had 600 m/s horizontal velocity, the gravitational force creates an acceleration vertically downwards, it will not alter the horizontal velocity.
So the time taken by the bullet to cover a horizontal displacement 200m will be equal to

time = 200/600 = 1/3 seconds

Mean while the vertical motion of the bullet is accelerated
vertical displacement of the bullet = h = ut+(1/2)a(t^2)
u = 0 m/s
a = g = 9.8 m/s
t = 1/3 s
h = 0.5 x 9.8 x (1/9) = 0.544 m (Ans)

(Correction in picture v = 600 m/s)

Answer 2

Answer:

time = 200/600 = 1/3 seconds

Mean while the vertical motion of the bullet is accelerated

vertical displacement of the bullet = h = ut+(1/2)a(t^2)

u = 0 m/s

a = g = 9.8 m/s

t = 1/3 s

h = 0.5 x 9.8 x (1/9) = 0.544 m=49/90m