1.

Consider a particle of mass m having linear momentum `vecp` at position `vecr` relative to the origin O. Let `vecL` be the angular momentum of the particle with respect to the origin. Which of the following equations correctly relate(s) `vecr`, `vecp` and `vecL`?A. `(dvecL)/(dt) + vecr xx (dvecp)/(dt)=0`B. `(dvecL)/(dt) + (dvecr)/(dt) xx vecp=0`C. `(dvecL)/(dt) - (dvecr)/(dt) xx vecp=0`D. `(dvecL)/(dt)- vecr xx (dvecp)/(dt)=0`

Answer» Correct Answer - d
As `vecL= vecr xx vecp`
Differentiate both sides with respect to time, we get
`(dvecL)/(dt) - d/(dt) (vecr xx vecp) = (dvecr)/(dt) xx vecp + vecr xx (dvecp)/(dt)`
`=vecr xx (dvecp)/(dt)`
`therefore (dvecr)/(dt) xx vecp=0`
`(dvecL)/(dt) - vecr xx (dvecp)/(dt)=0`


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