The boy of mass 40 kg is sliding down the spiral slide at a constant speed such that his position, measured from the top of the chute, has components r = 1.5 m, θ = (0.7t) rad, and z = (-0.5t) m, where t is in seconds. Determine the components of force Fr, Fθ, and Fz which the slide exerts on him at the instant t = 2 s. Neglect the size of the boy.