Question 36:
(a) Define momentum of a body. On what factors does the momentum of a body depend ?
(b) Calculate the change in momentum of a body weighing 5 kg when its velocity decreases from 20 m/s to 0.20 m/s.


(a). Momentum is a physical quantity that states the measure of the motion of a body. It depends on the mass and velocity of the moving body. 

If a body of mass $m$ is moving with a velocity of $v$ then,

The momentum of the body $P=m\times v$

Momentum is a vector quantity. Its SI unit is $kg-m/s$.

(b) Here given, the mass of the body $m=5\ kg$

Initial velocity $v_1=20\ m/s$

Final velocity $v_2=0.2\ m/s$

Therefore, change in momentum $=P_1-P_2$

$=mv_1-mv_2$

$=m(v_1-v_2)$

$=5(20-0.2)$

$=5\times19.8$

$=90\ kg-m/s$

Therefore, change in momentum after decreasing the velocity from $20\ m/s$ to $0.2\ m/s$ is $90\ kg-m/s$.

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Updated on: 10-Oct-2022

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