Q3: A block of mass m - 6.00 kg is released from rest from point and slides on the frictionless track shown in the figure below. (Assume ha-6.20 m.) 3.20 m 2.00 m (a) Determine the block\'s speed at points B and C. (b) Determine the net work done by the gravitational force on the block as it moves from point point C. to Solution Speed at point B ETot = KE + U KE = (1/2) m v^2 U = m g h ETot, A = 0 + (6 kg)(9.8 m/s^2)(6.2 m) = 364.56 J ETot = 364.56 J = constant ETot, B = (1/2)(6 kg)(vB^2) + (6 kg)(9.8 m/s^2)(3.2 m) (1/2)(6 kg)(vB^2) + 188.16 J = 364.56 J vB = 7.67 m/s speed at point C ETot, C = (1/2)(6 kg)(vC^2) + (6 kg)(9.8 m/s2)(2.0 m) (1/2)(6 kg)(vC^2) + 117.6 J = 364.56 J vC = 9.07 m/s b) WAC = m g h WAC = (6 kg) ( 9.8 m/s2) (6.2 m - 2.0 m) WAC = (6 kg) ( 9.8 m/s2) (4.2m) WAC = 246.96 J .