The uniform slender bar ABC weighs 6 lb and is initially at rest with end A bearing

Question:

The uniform slender bar ABC weighs 6 lb and is initially at rest with end A bearing against the stop in the horizontal guide. When a constant couple M = 72 lb-in. is applied to end C, the bar rotates causing end A to strike the side of the vertical guide with a velocity of 10 ft /sec. Calculate the loss of energy ΔE due to friction in the guides and rollers. The mass of the rollers may be neglected.