Question

A bullet is fired horizontally on a 150 m away target with a speed of 1500 m/s. how much below does the bullet hit the target ? (g = 10 m/s2)

Answer 1

This is can be solved with help of horizontal projectile concept.
In horizontal, acceleration act on bullet is zero.
so, distance = speed of bullet × time taken
150 = 1500 × t
t = 0.1 sec , hence bullet strikes the ground in 0.1 sec

Now , how much below does the bullet hits the target.
Let bullet hits the target h m below ,
in vertical, initial velocity = 0 and acceleration = -g
so, use formula ,
S = ut + 1/2at²
h = 0 - 1/2 × g × (0.1)² = 1/2 × -10 × 0.01 m = -5cm , here negative sign indicates bullet does hit below the reference level.

Hence answer is 5cm

Answer 2

Hi ,

it is given that ,

distance traveled the bullet to reach the target ( d ) = 150 m

speed of the bullet ( v ) = 1500 m / s²

g = 10 m/s²

time taken to reach the target ( t ) = d/v


  t = 150/1500 = 1/10 = 0.1 sec

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We know that ,

s = ut + 0.5 gt²

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since u = 0 , 

s = ut + 0.5 gt²

s = 0.5 gt²

   = 0.5 × 10 × ( 0.1 )²

   = 5/100 m

   = ( 5/100 ) × 100cm

   = 5 cm

The bullet should be fired 5 cm below the target .

I hope this helps you.

: )