At what speed does a bullet fly out of a gun when fired, if the mass of gunpowder is 4 g

At what speed does a bullet fly out of a gun when fired, if the mass of gunpowder is 4 g, and the mass of the bullet is 20 g?

These tasks: m1 (mass of gunpowder in the cartridge) = 4 g (in SI m = 0.004 kg); m2 (bullet weight) = 20 g (in SI m2 = 0.02 kg); for the calculation, we assume that all the energy from the combustion of gunpowder goes to increase the kinetic energy of the bullet.

Reference values: q (specific heat of combustion of gunpowder) = 0.38 * 107 J / kg.

We express the sought speed of bullet exit from the gun from the equality: Ek = Q and m2 * V2 / 2 = q * m1, whence V = √ (2 * q * m1 / m2).

Let’s calculate: V = √ (2 * 0.38 * 107 * 0.004 / 0.02) ≈ 1233 m / s.