A 7.00 gram bullet, when fired from a gun into a 1.20 kilogram block of wood held in a vise, penetrates the block to a depth of 9.00 centimeter. This block of wood is next located on a frictionless horizontal surface, and a second 7.00 gram bullet is fired from the gun into the block. Find to what depth will the bullet penetrate the block in this case?
cm