Question

A particle is moving with a momentum of $10kgm/s$. A force of $0.2N$ acts on it in the direction of motion of the particle for $10s$. If the mass of the particle is $5kg$, the increase in kinetic energy is (in J)

• A. $4.4$
  
• B. $3.2$
  
• C. $3.8$
  
• D. $2.8$
  

Answer 1

The correct option is A $4.4$

Initial KE $=\frac{p^2}{2m}=\frac{{10}^2}{2\times 5}=10J$

Initial velocity $u=\frac{p}{m}=10/5=2m/s$

Acceleration $=a=F/m=0.2/5=0.04m/s^2$

Final velocity $=v=u+at=2+(0.04\times 10)=2.4m/s$

Final KE $=0.5\times m\times v^2=14.4J$

Increase in KE $=14.4-10=4.4J$

Hence correct answer is option $A$