Q.

A body of mass 2 kg begins to move under the action of a time dependent force given by F=(6ti^+6t2j^)N. The power developed by the force at the time t is given by           [2024]

1 (6t4+9t5)W  
2 (3t5+6t5)W  
3 (9t5+6t3)W  
4 (9t3+6t5)W  

Ans.

(4)     

          F=(6ti^+6t2j^)N

          F=ma=(6ti^+6t2j^)

          a=Fm=(3ti^+3t2j^)

          v=0tadt=3t22i^+t3j^

         P=F·v=(9t3+6t5)W