# A hunter fires a gun from a moving boat in the direction of its movement. What speed did the boat have if it stopped

A hunter fires a gun from a moving boat in the direction of its movement. What speed did the boat have if it stopped after three quick shots one after the other? the mass of the boat together with the hunter is 100 kg, the mass of the charge is 20 g, the average velocity of shot and powder gases is 500 m / s.

Given:

m1 = 100 kilograms – the mass of the hunter together with the boat;

m 2 = 20 grams = 0.02 kilograms – the mass of the gun charge;

n = 3 – the number of shots after which the boat stopped;

v2 = 500 meters per second – average velocity of shot and powder gases.

It is required to determine v1 (meter per second) – the initial speed of the boat.

Since by the condition of the problem after n shots the boat stopped, then by the law of conservation of momentum (momentum) we find:

m1 * v1 = n * m2 * v2, hence:

v1 = n * m2 * v2 / m1 = 3 * 0.02 * 500/100 =

= 3 * 0.02 * 5 = 3 * 0.1 = 0.3 meters per second.

Answer: the initial speed of the boat was 0.3 meters per second.

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