A bullet when fixed at a target with a velocity of `100 ms^(-1)`, penetrates one metre into it. If the bullet is fired with the same velocity as a similar target with a thickness `0.5` metre, then it will emerge from it with a velocity of

Options

A. `50sqrt2 m s^(-1)`
B. `(50)/(sqrt2) m s^(-1)`
C. `50 m s^(-1)`
D. `10 m s^(-1)`

Answer

A

Explanation

`(1)/(2) m xx 100 xx 100 = f xx 1 or f = 5000 m N`
Again `(1)/(2)mv^(2) - (1)/(2)mv^(2) = f xx 0.5`
or `m[v^(2) - v'^(2)] = fxx 1`
or `v'^(2) = v'^(2) -5000`
or `v'^(2) = 10000 - 5000`
or `v'^(2) = 5000`
or `v'^(2) = 2500`
or `v'^(2) = 50 sqrt2 ms^(-1)`