question_answer

A particle of mass 2 kg is moving such hat at time t, its position, in meter, is given by \[\overset{\to }{\mathop{\operatorname{r}}}\,(\operatorname{t})=5\hat{i}-2{{\operatorname{t}}^{2}}\hat{j}.\] The angular momentum of the particle at \[\operatorname{t}=2s\] about the origin in kg \[{{\operatorname{m}}^{-2}}\]\[{{\operatorname{s}}^{-2}}\] is:                                        [JEE ONLINE 23-04-2013]

A)   \[-80\hat{k}\]  

B)        \[\left( 10\hat{i}-16\hat{j} \right)\]

C)  \[-40\hat{k}\]   

D)        \[40\hat{k}\]­­

Correct Answer: A

Solution :

[a] Angular momentum