A bullet weighing 12 g hits an obstacle and goes deep into it by 6 cm. What is the resistance

A bullet weighing 12 g hits an obstacle and goes deep into it by 6 cm. What is the resistance force of the obstacle, if its initial velocity is 520 m / s.

The work of the resistance force of the obstacle A is equal to the kinetic energy of the bullet:

A = E = M V1 ^ 2/2,

where M is the mass of the bullet, M = 12 g = 0.012 kg;

V1 is the speed of the bullet to the obstacle; V1 = 520 m / s.

On the other hand, work A is equal to the product of the average resistance force F by the thickness of the bullet deepening into the obstacle s = 6 cm = 0.06 m:

A = Fs.

Obstacle resistance force F:

F = A / s = M V1 ^ 2 / (2 s) = 0.012 × 520 ^ 2 / (2 × 0.06) = 27040 N = 27.04 kN.

Answer: 27.04 kN.