Question

A particle of mass `2 kg` located at the position `(hati + hatj)m` has velocity `2(hati - hatj + hatk) m//s` . Its angualr momentum about Z-axis in `kg m^(2)//s` is
A. `+4`
B. `- 8`
C. `+ 8`
D. `- 4`

Answer 1

Correct Answer - B
About origin, angular momentum will be
`overset rarr(L) = m(overset rarr(r ) xx overset rarr(v)) = 2(hati + hatj) x 2(hati - hatj + hatk)`
`= 2 |[hatj,hatj, hatk],[1,1,0],[2,-2,2]| = 4 hati - 4 hatj - 8 hatk`
Component of angular mometnum about Z-axis,
`L_(z) = - 8 kg m^(2)//s`.