Question

The century-old ascensores in Valparaiso, Chile, are small cable cars that go up and down the steep hillsides. As the figure(Figure_1) shows, one car ascends as the other descends. The cars use a two-cable arrangement to compensate for friction; one cable passing around a large pulley connects the cars, the second is pulled by a small motor. Suppose the mass of both cars (with passengers) is 1700 kg, the coefficient of rolling friction is 3.0 times 10^-2, and the cars move at constant speed. What is the tension in the connecting cable? Express your answer to two significant figures and include the appropriate units. What is the tension in the cable to the motor? Express your answer to two significant figures and include the appropriate units.

Answer 1

Part A As the system is not accelerating,the tension is the weight of the cart plus twice the friction T-mg sin θ +2μmg sin θ As the angle is not given assume it to be 90 -1700x(98+0.03x9.8) T. =17159.8 N Part B The motor should give enough tension to overcome the friction 2 ×0.03× 1700× 9.8 In = 9996 N