Question

A shot travelled at a rate of 100m/s pierced a plunk of 4cm thick. what is the velocity of shot to pierce a 9cm thick?

Answer 1

Let a uniform deceleration provided to the shot be`=a" ms"^-2`

Inserting given values in kinematic expression in SI units as below we get

`v^2-u^2=2as`
`0^2-100^2=2axx4/100`
`=>a=-100^2xx100/8=-125000" ms"^-2`

Again to calculate required velocity to pierce `9cm` we use the same equation and get

`0^2-u^2=2(-125000)9/100`
`=>u=sqrt(1250xx18)`
`=>u=150" ms"^-1`