Question

A body of mass` 5 kg` is moving with a momentum of `10 kg m//s`. A force of `0.2 N` acts on it in the direction of motion of the body for `10 sec.` The increase in its kinetic energy.
A. `2.8 J`
B. `3.2 J`
C. `3.8 J`
D. `4.4 J`

Answer 1

Correct Answer - D
Initial K.E.`=(p_(1)^(2))/(2m)=(10xx10)/(2xx5)=10J`
Impulse `=p_(2)-p_(1)=Fxxt`
`p_(2)-10=0.2xx10, p_(2)=12 kg m//s`
Final `K.E.=(p_(2)^(2))/(2m)=(12xx12)/(2xx5)=14.4J`