A 75.0 kg mountain climber is holding his 60.0 kg partner over a cliff when he suddenly steps on the ice with a coefficient of kinetic friction of 0.300 at the horizontal top of the cliff, as shown in the accompanying figure. The rope has negligible mass and is held horizontally by the climber. There is no appreciable friction at the icy edge of the cliff. Use energy methods to calculate the speed of the climbers after the lower one has descended 1.80 m starting from rest. What would be the speed of the climbers after they had moved 1.80 m?