A particle moves in the x-y plane under the action of a force F→ such that the value of its linear momentum P→ at any time t is Px = 2 cos t, Py = 2 sin t. The angle θ between F→ and P→ at a given time t will be

P = Px2+Py2 = (2 cos t)2+(2 sin t)2 = 2If m be the mass of the body, thenKinetic energy = P22m = (2)22m = 2 mSince kinetic energy does not change with time, both work done and power are zero.Now Power = Fv cos θ = 0As  F ≠0, v ≠0            ∴cos θ or θ = 900As direction of P→ is same that v→ (∴ P→ = mv→), hence angle between F→ and P→ is equal to 900