The 4-kg slender bar is pinned to a 2-kg slider at A and to a 4-kg homogeneous cylindrical disk at B. Neglect the friction force on the slider and assume that the disk rolls. If the system is released from rest with \theta=60^\circθ=60 ∘ , find the value of work in J done by the slender bar's weight when \theta=0θ=0? Keep the result with two significant digits. Hint: U=-mg\left(y_2-y_1\right)U=−mg(y 2 −y 1 ) where yy represents the height of the center of gravity.