Question 188: Laws of Motion

Question

A machine gun fires a bullet of mass 35 gram with a speed of $600 \mathrm{~m} / \mathrm{s}$. The person holding the gun can extract a maximum force of 147 N on it. The number of bullets that can be fired from the gun per second is

Accepted Answer

1. Given data:
Mass of bullet, $ m = 35\, 	ext{g} = 0.035\, 	ext{kg} $
Speed of bullet, $ v = 600\, 	ext{m/s} $
Maximum force person can apply (i.e. average resisting force), $ F = 147\, 	ext{N} $
We want: number of bullets per second, i.e. rate of fire $ n $.
2. Momentum per bullet:
Impulse per bullet = change in momentum of one bullet =
$ \Delta p = m v = 0.035 	imes 600 = 21\, 	ext{kgÃÂ·m/s}. $
3. Time rate of momentum (Force):
When $ n $ bullets are fired per second, the rate of momentum imparted per second is $ n 	imes 21 $.
This equals the average force:
$ F = n \Delta p $
So,
$ 147 = n 	imes 21 $
$ n = \frac{147}{21} = 7. $
Answer:
$ \boxed{7} $
So the correct option is
C (7)
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Answer

3

Answer

5

Answer

7

Answer

9

Laws of Motion

A machine gun fires a bullet of mass 35 gram with a speed of 600 \mathrm{~m} / \mathrm{s}. The person holding the gun can extract a maximum force of 147 N on it. The number of bullets that can be fired from the gun per second is

Choose the correct answer: