Question

Energy of a Bullet Dissipated by Plywood. As part of a criminal investigation, you need to determine how much of a bullet’s energy is dissipated by a 0.500-inch piece of plywood. You construct a device that consists of three disks that are separated by a distance d = 0.950 m and rotate on a common axis. The bullet is fired through the first disk (a few inches above its center), which is composed of a light plastic that has a negligible effect on the speed of the bullet. The bullet then passes through the second disk, which is composed of 0.500-inch plywood. Finally, the bullet strikes the third disk, where it becomes embedded. The disks rotate with an angular velocity of ω = 80.0 rad/s. The angular displacement between holes in the first and second disks is Δθ₁₂ = 0.244 rad, and the angular displacement between the
holes in the second and third disks is Δθ₂₃ = 0.262 rad.

If the mass of the bullet is 14.0 g, find (a) the initial speed of the bullet and (b) the energy dissipated by the 0.50-inch plywood.

Answer 1