1. The efficiency of a squeaky pulley system is 73 percent. The pulleys are used to raise a mass to a certain height. What force is exerted on the machine if a rope is pulled 18.0 m in order to raise a 58 kg mass a height of 3.0 m?
Answer: 13.24 N?
A person lifts a 950 N box by pushing it up an incline. If the person exerts a force of 350 N along the incline, what is the mechanical advantage of the incline?
Answer: 2.71?
1. There is an ideal mechanical advantage of 18/3 = 6 in this case. The ideal force required to balance the Mg = 58*9.8 = 568.4 N weight would be 568.4/6 = 94.7 N. Because of the 73% efficiency, the actual force required is 1/0.73 = 1.37 times higher, or 129.7 N
2. 2.71 is correct
1 answer
130 N
1 answer