A machine gun fires a bullet of mass 40 g with a velocity 1200 m/s. The man holding it can exert a maximum force of 144 N on the gun. How many bullets can he fire per second at the most?
Correct answer: D. Three
- A. One
- B. Four
- C. Two
- D. Three
Explanation
To solve this problem, we use the principle of momentum. The momentum imparted by each bullet is given by mass × velocity = 0.04 kg × 1200 m/s = 48 kg·m/s. The change in momentum per second is equal to the force applied: F = Δp/Δt. If the man fires 'n' bullets per second, the total momentum change per second is n × 48 kg·m/s. Setting this equal to the maximum force, 144 N = n × 48, we find n = 3. Therefore, the correct answer is three bullets per second. The other options either underestimate or overestimate the number of bullets based on the force calculation.
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