1. The efficiency of a lifting machine is 80%. If the velocity ratio of the machine is 15, what is mechanical advantage of the machine?

2. Figure shows a differential wheel and axle. In this three drums of diameter D, d₁and d₂ mounted rigididly on a shaft supported on bearings. One string is wound on the largest diameter drum and other strings is wound on the other drums passing through a pulley. When the string on the largest diameter drum is unwound by applying an effort P , due to rotaion of the drum, the other string starts unwinding on diameter d₂ and winding on diamter d₁. The weight W is lifted. Find out the velocity ratio of the machine.