Question

A `5.0g` bullet moving at `100m//s` strikes a log. Assume that the bullet undergoes uniform deceleration and stops in `6.0cm`. Find (a) the time taken for the bullet to stop, (b) the impulse on the log and (c) the average force experienced by the log.

Answer 1

Correct Answer - A::B::C::D
(a) `v^2=u^2-2as`
`:. a=(u^2)/(2s)` `(v=0)`
`=((100)^2)/(2xx0.06)=8.3xx10^4m//s^2`
`v=u-at`
`0=u-at`
or `t=u/a=(100)/(8.3xx10^4)`
`=1.2xx10^-3s`
(b) `Impu lse=|Deltap|=mv_i`
`=(5xx10^-3)(100)`
`=0.5N-s`
(c) `Impu lse=(F_(av))t`
`:. F_(av)=(Impu lse)/(t)`
`=(0.5)/(1.2xx10^-3)`
`=417N`