A bullet weighing 10g is fined with a velocity of `800ms^(-1)`. After passing through a mud wall 1m thick, its velocity decreases to `100ms^(-1)`. Find the average resistance offered by the mud wall.

Explanation

Mass of bullet,
`m=10g=0.01kg`
Velocity of bullet before passing through mud wall, `u=800ms^(-1)`
Velocity of bullet after passing through mud wall,
`v=100ms^(-1)`
Distance covered by the bullet,
`s=1m`
Let average resistance offered by the wall = F
According to work-energy theorem,
`{:("Work done by"),("resistance offered"),("by mud wall"):}}={{:("Decrease"),("in K.E"):}`
or `Fs=(1)/(2)m(u^(2)-v^(2))`
Average resistance
`therefore F=(m(u^(2)-v^(2)))/(2s)`
`=(0.01xx(800^(2)-100^(2)))/(2xx1)`
`=3150N`