question_answer

A body of mass 20 kg moving with a velocity of 10 m/s is brought to rest after some time. Find the change in momentum of the body.

Answer:

Given, Mass of the body (m) = 20 kg Initial velocity of the body (u) = 10m/s Body is stopped\[400\times 72+4000\times 9=400\times 18+4000\times {{V}_{T}}\]Final velocity of the body\[\Rightarrow \] To know the change in momentum, we should know the Initial momentum and Final momentum We know that Momentum \[(P)=mass(m)\times velocity(v)\] \[\Rightarrow \]Initial momentum\[({{P}_{1}})\]= mass (m) × initial velocity\[(u)=20\times 10=200\,\,kg\,\,m/s\] Final momentum\[({{P}_{2}})=mass\,(m)\times final\] velocity \[(v)=20\times 0=0\] Change in momentum = Final momentum - Initial momentum \[=0-200=200\,\,kg\,\,m/s\] Understanding: negative sign indicates the motion of the body in opposite direction of the force.