A bullet of mass 25kg strikes horizontally an immovable block of wood with a velocity of 250m/s and penetrates it a distance of 1m. Calculate the resistance of the wood on the bullet , assuming the resistance to be uniform. How far would the bullet have penetrated , if its had been 200m/s ?

Answer 1

mass of the bullet is m = 25 kg (???)
mv²/2 =F(res)•d
F(res) = mv²/2d
d₁= mv₁²/2•F(res)