Question

A body of mass 20*10-3 Kg when acted upon by a force for 4 seconds, attains a velocity of 100 m/s. if the same force is applied for 2 minutes,on a body of mass 10 Kg at rest, what will be its velocity?

Answer 1

Net force on the body is F=3t2−32

so net acceleration will be a=mF=0.3t2−3.2

We know that acceleration is  a=dtdv   so dv=adt

integrating both sides we get ∫v=10Vdv=∫t=0t=5(0.3t2−3.2)dt 

we get the new velocity after 5s as V=10+30.3(53−0)−3.2(5−0)

or V=6.5m/s