14-76. A 50-kg barrel (Ic 2.25 kg-m) starts from rest and is restrained by mass B, which is sup- ported by a cable wound around the barrel as shown (Figure P14-76). Determine the mass of B so that the barrel has a velocity of 1.2 m/s at the bottom of the slope. FIGURE P14-76 B A 50 kg 5 m .6 m 14-80. The spring is stretched 0.2 m from free length in the position shown (Figure P14-80). Ic= 1.12 kg-m for cylinder A. If there is no slipping and the system is released from rest, find the velocity of B after it has moved 0.25 m. .3 m .1 m FIGURE P14-80 100 kg K=150 N/m Block B is moving up! Pay attention here as there is loss in A Potential Energy. B gains potential energy. Please make sure you understand this. B 10 kg Neglect Friction Work Spring: Once you find displacement of spring then add the original displacement of 0.2m to get total displacement. The energy term: 1/2k (s2-s1)^2 Where s2 is total and s1 is original