Question

A bullet of 5g , travelling at a speed of 100 m/s penetrates a wooden block up to 6.0 cm. Then the average force applied by the bullet on the block is-
a) 417 N
b) 8333 N
c) 83.3 N
d) 0

Answer 1

v²= u² + 2as

2as = v²- u²

2 x a x (6/100) = 0 - (100)²

12a / 100 = - 10000

a = -1000000 / 12 m/s²

This is the average retardation of the bullet

Avg force F = m a

= (5/1000) x 1000000 / 12 = 416.66 N

Approx 417 newton
So the answer is: a)417 N

Hope it helps!!

Answer 2

a = (v^2 - u^2) / (2S)
a = -u^2 / (2S)
a = -100^2 / (2 * 0.06)
a = -83333 m/s^2
Magnitude of retardation = -a = 83333 m/s^2

F = m(-a)
F = 0.005 * 83333
F = 416.65 N
F ≈ 417 N

Correct option is (a) 417 N