Question

A bullet fired into a fixed target loses half of its velocity in penetrating 15cm. How much further it will penetrate before coming to rest

Answer 1

The correct answer for your question is 5 cm.

Your question:

A bullet fired into a fixed target loses half of its velocity in penetrating 15cm. How much further it will penetrate before coming to rest?  

Solution:

Let us consider the ‘u’ as the initial velocity of the bullet.

u/2 as the velocity of the bullet after penetrating 15cm through the object

Applying the Equation of motion for the initial velocity of the bullet

v²=u²+2aS  

a=−u2/40

Applying the equation of motion for the bullet after penetrating 15cm

v²=u²+2aS

Here, u = o where the bullet is at the rest

The initial velocity of the bullet after penetrating 15cm is u/2

Applying the data in the equation of motion

We get

v²=u²+2aS

⟹ u2/20 S=u2/4

⟹ S = 5 cm.

Answer 2

v^2=u^2+2as

u2/20s =us /4

s=5cm