The time dependence of the position of a particle of mass m = 2 is given by   r   → t = 2 t…

The time dependence of the position of a particle of mass m=2 is given by  r →t=2t i^-3t2j^ . Its angular momentum, with respect to the origin, at time t=2  is:
  1. 36 k^
  2. 48 i^+j^
  3. -48 k^
  4. -34 k^-i^

Solution

r→=2t i^-3t2 j^
v→=2 i^-6t j^
Momentum p→=mv→
=4 i^-12t j^
∴ angular momentum L→=r→×p→
=2t i^-3t2 j^×4 i^-12t j^
=-24t2 k^+12t2 k^
=-12t2 k^
At time t=2
L→=-48 k^

Asked in: JEE Main 2019 (10 Apr Shift 2)

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