An average force of $125 \mathrm{~N}$ is applied on a machine gun firing bullets each of mass $10 \mathrm{~g}$ at the speed of $250 \mathrm{~m} / \mathrm{s}$ to keep it in position. The number of bullets fired per second by the machine gun is :

<p>To find the number of bullets fired per second, we can use the concept of momentum. When the machine gun fires bullets, it experiences a backward force due to the conservation of momentum. The force applied on the machine gun is used to balance this backward force.</p> <p>First, let&#39;s find the momentum of each bullet:</p> <p>Momentum = Mass × Velocity</p> <p>Bullet mass = $10 \mathrm{~g} = 0.01 \mathrm{~kg}$ Bullet velocity = $250 \mathrm{~m/s}$</p> <p>Momentum per bullet = $0.01 \mathrm{~kg} \cdot 250 \mathrm{~m/s} = 2.5 \mathrm{~kg \cdot m/s}$</p> <p>Now let&#39;s find the momentum per second that needs to be balanced by the applied force:</p> <p>Force = $125 \mathrm{~N}$</p> <p>Momentum per second = Force × Time</p> <p>Since we are considering a time interval of 1 second, the momentum per second is equal to the applied force:</p> <p>Momentum per second = $125 \mathrm{~N}$</p> <p>Now, let&#39;s find the number of bullets fired per second:</p> <p>Number of bullets = Momentum per second / Momentum per bullet</p> <p>Number of bullets = $\frac{125 \mathrm{~N}}{2.5 \mathrm{~kg \cdot m/s}}$</p> <p>Number of bullets = 50</p> <p>Therefore, the machine gun fires 50 bullets per second.</p>