Q.

A force of -Pk^ acts on the origin of the coordinate system. The torque about the point (2, - 3) is P(ai^+bj^), the ratio of ab is x2. The value of x is _____ .        [2023]


Ans.

(3)

τ=r×F

Where r=-2i^+3j^

τ=(-2i^+3j^)×(-Pk^)=P(-2j^-3i^)=P(-3i^-2j^)

So a=-3, b=-2

ab=32