## pratu043 3 years ago A machine gun fires 25 g bullets at the rate of 600 bullets per minute with a speed of 200 m/s. Calculate the force required to keep the gun in position.

1. Yahoo!

600 bullets per minute = 600/60 = 10 bullets per second F = n * m * v = 10 * 200 * 25 * 10^-3 = 2N

2. pratu043

But force is rate of change of momentum right?

3. Yahoo!

sorry F=50N

4. Mikael

He gave you in fact Change of momentum/ per 1 sec

5. Yahoo!

My calcu was wrong..))

6. pratu043

I didn't get you @Mikael.

7. Mikael

See he calculated for U how much Momentum is given to ALL the bullets flying-out in the period of 1 second . IT IS the change in momentum of the gun too - with a minus sign of course

8. RaphaelFilgueiras

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9. RaphaelFilgueiras

impulse is the variation of momentum

10. RaphaelFilgueiras

think in one bullet

11. Rohangrr

\[-- ♬ \ Jack \ of \ Oz \ ♬ \ [your \ turn] \]

12. TheProf

If the slowest rate of acceleration of a bullet is 0.1 seconds, then 0.025 x (200/0.1) [F = ma] = 50 N. So that would be the force from each fired bullet. We get the 0.1 second as the gun fires 10 rounds per second.

13. ghazi

force exerted by each bullet is impulsive therefore...force exerted by each bullet is 5 N that is the force which should be maintained to keep gun stationary