A bullet of mass 25 g moving with a velocity of `400 ms^(-1)` strikes a cardboard and goes out from the other end with a velocity of `300ms^(-1)`, find out the work done in passing through the cardboard.

Explanation

Mass of the bullet (m) = 25 g
Initial velocity `(u)=400 ms^(-1)`
Final velocity `(v)=300 ms^(-1)`
Work done (w) = ?
From work - energy theorem,
Work done = loss in kinetic energy,
`W=(1)/(2)m(u^(2)-v^(2))=(1)/(2)xx(25)/(1000)xx(400^(2)-300^(2))`
`=(1)/(2)xx0.025xx(16xx10^(4)-9xx10^(4))`
`=(1)/(2)xx0.025xx(7xx10^(4))=0.0125xx(7xx10^(4))`
Workdone (W) = 875 J