Q.
A rifle of 20kg mass can fire 4 bullets per second. The mass of each bullet is 35×10−3kg and its final velocity is 400ms−1. Then what force must be applied on the rifle so that it does not move backwards while firing the bullets?
3073
258
EAMCETEAMCET 2007Laws of Motion
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Solution:
From conservation of momentum MV+(4mv)=0 ⇒V=−M4mv=−204×35×10−3×400 =−2.8ms−1
Force applied on the rifle, F=tMV=−120×2.8 =−56N