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?

1 Answer
Jan 25, 2018

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#