Question

Two paper screens (1) and (2) are separated by a distance of 100 m. A bullet pierces () and )
the hole (2) is 10 cñ below the hole (1). If the bullet is travelling horizontally at the time of hitting (1).
Then velocity of the bullet at (1) is
(1) 100 m/sec (2) 200 m/sec (3) 600 m/sec (4) 700 m/sec​

Answer 1

Let x = 100 m and h = 10 cm

Using equation of motion we can then calculate the time of the motion as,

h = ut + 1/2 gt²

So we will then assume initial velocity to be zero and g = 10 m/s²

We will get

t = √2h/g

t = √2 x 10 cm/ 10 m/s²

t = √2 x 0.1 m / 10m/s²

t = 0.14 s

Now again we will use equation of motion as,

x = vt or v = x/t

we get,

v = 100 m/0.14 s

v = 707.11 m/s