Question

A bullet of mass 10kg velocity=100m/s strikes a mud wall and rest after penetrating through 5m . What is the force of wall ?

Answer 1

u = 100m/s

v = 0m/s

using ,

v²-u² = 2as

-u² = 2as

-10000 = 10a

a = -1000m/s²

⇒F = ma

⇒F = 10×-1000

⇒F = -10000N

Answer 2

Answer: F=1000N

Explanation: Since, finally the bullet stops, therefore

loss in kinetic energy = initial kinetic energy.

Let F be the average resisting force ,m=10 g or 0.01kg  ,S=5 cm =0.05m

So  

2

mv

2

​

=FS⇒

2

0.01×100

2

​

=F×0.05

So F=1000N