A bullet weighing 10 g has a velocity of 400 m / s. At what speed will the bullet continue to move

A bullet weighing 10 g has a velocity of 400 m / s. At what speed will the bullet continue to move after piercing a 5 cm thick board, if the average resistance force of the board is 12 kN?

Data: m (bullet mass) = 10 g = 0.01 kg; V1 (speed before hitting the board) = 400 m / s; h (board thickness) = 5 cm = 0.05 m; F (average resistance force of the board) = 12 kN (12 * 103 N).

To determine the speed of the bullet after piercing the board, we use the equality: m * V1 ^ 2/2 – m * V2 ^ 2/2 = A = F * h; m * V2 ^ 2/2 = m * V1 ^ 2/2 – F * h and V2 = √ (2 * (m * V1 ^ 2/2 – F * h) / m).

Calculation: V2 = √ (2 * (0.01 * 400 ^ 2/2 – 12 * 10 ^ 3 * 0.05) / 0.01) = 200 m / s.

Answer: The bullet will continue to move at a speed of 200 m / s.