In a design test of penetration resistance, a 12-g bullet is fired through a 400-mm stac...

In a design test of penetration resistance, a 12-g bullet is fired through a 400-mm stack of fibrous plates with an entering velocity of 600 m/s. If the bullet emerges with a velocity of 300 m/s, calculate the average resistance R to penetration. What is the loss Δq of energy and where does it go?