We know that angular momentum, →L=→r×→p .....(1)
→r(t)=2t^i−3t2^j
At t=2 s, →r=4^i−12^j m
Velocity of particle, →v=→dr→dt=2^i−6t^j
At t=2 s, →v=2^i−12^j m/s
Now linear momentum,
→p=m→v=4^i−24^j .........(2) [ m=2 kg ]
From Eq. (1) and (2),
→L=→r×→p
→L=∣∣
∣
∣∣^i^j^k4−1204−240∣∣
∣
∣∣
→L=^i(0−0)−^j(0−0)+^k(−96−(−48))
⇒→L=−48^k kg.m2/s
Since, →L=−N^k kg.m2/s
Hence on comparing we get,
⇒N=48