The power of a gun which fires 120 bullet per minute with a velocity 120 ~ms ⁻¹ is : (given the mass of each bullet is 100 ~g )

Step-by-step solution

The number of bullets fired per second is n = 120 60 = 2 bullets per second. The mass of each bullet is m = 100 g = 0.1 kg . The velocity of each bullet is v = 120 ms ⁻¹ . The kinetic energy of one bullet is K = 1 2 mv^2 = 1 2 0.1 (120)^2 = 0.05 14400 = 720 J . The power of the gun is the total kinetic energy delivered per second, which is P = n K = 2 720 = 1440 W . Converting to kilowatts, P = 1440 1000 kW = 1.44 kW . Answer: 1.44 kW