A bullet of mass 20gram strikes a target with a velocity of 100m`//`s and is brougth to rest after piercing 20cm into it. What is the average force of resistance offered by the target?

Explanation

Here, `m=20g=(20)/(1000)kg=(1)/(50)kg, u=100m//s,v=0,s=20cm=(1)/(5)m,F=?`
According to word energy theorem, `Fxxs=(1)/(2)m(v^(2)-u^(2)) `
`F=(m)/(2s)(v^(2)-u^(2))=(1)/(50xx2xx1//5)(0-100^(2))F=(-100xx100)/(20)=-500N`
Negative sign represents opposing force.