A bullet going 153 m/s crashes through a wood plank. After passing through the plank, its speed is 130 m/s. Another bullet, of same mass and size traveling at 92 m/s is also fired at the plank.

What will this second bullet's speed be after tunneling through?

Assume

1.) The resistance of the plank is independent of the speed of the bullet.

2.) The plank does the same amount of work on the two bullets.

What will this second bullet's speed be after tunneling through?

Assume

1.) The resistance of the plank is independent of the speed of the bullet.

2.) The plank does the same amount of work on the two bullets.

Work done by the plank on the bullet = change in Kinetic energy.

Let m = mass of bullet. Find the change in kinetic energy of the first bullet in terms of m.

Let v = final speed of the second bullet. Then the final kinetic energy of the this bullet = 1/2 mv^2.

Find the change in kinetic energy of the second bullet.

Equate the change in KE of first bullet with change in KE of second bullet. Solve for v.