When a bullet of mass 10 g and speed 100 m/s penetrates up to distance 1 cm in a human body in rest . The resistance offered by human body is
Here u = 100 m/s
v = 0, s = 1 cm = `10^-2` m
`:.` ` v^2 = u^2 - 2as`
`:.` `a =( u^2)/(2s) = (100 xx 100)/(2 xx 1 xx 10^-2`
= `5 xx 10^5` m / `s^2`
`:.` F = ma = `10 xx 10^-3 xx 5 xx 10^5` = 5000 N
Alternative method
`W = Delta `K
`or - Fs = 1/2 mv^2 - 1/2 mu^2`
= `0 - 1/2 xx 10 xx 10^-3 xx 10000`
or `- F xx 10^-2 = - 1/2 xx 10 xx 10^-3 xx 10 ^4`
`:.` F = 5000 N.
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