Rod OA rotates about O in a horizontal plane. The motion of the 400-g collar B is defined...

Rod OA rotates about O in a horizontal plane. The motion of the 400-g collar B is defined by the relations r = 500 + 300 sin πt and θ = 2π(t2 – 2t), where r is expressed in millimetres, t in seconds, and θ in radians. Determine the radial and transverse components of the force exerted on the collar when (a) t=0, (b) t = 0.8 s.