A bullet of mass 20 g has an initial speed of `1 ms^(-1)` just before it starts penetrating a mud wall of thickness 20 cm. If the wall offers a mean resistance of `2.5 xx 10^(-2)N` the speed of the bullet after emerging from the other side of the wall is close to:

Options

A. `0.7 m s^(-1)`
B. `0.4 m s^(-1)`
C. `0.1 m s^(-1)`
D. `0.3 m s^(-1)`

Answer

A

Explanation

`a = (-2.5 xx 10^(-2))/(20 xx 10^(-3)) " "v^2 = u^2 + 2as = 1^2 - (2 xx 2.5 xx 10^(-2))/(20 xx 10^(-3)) xx 20 xx 10^(-2) = 0.5 , v = 0.7 m//s` .