A roofer needs to get a stack of shingles onto a roof. Pulling the shingles up manually uses 1549 N of input force. The roofer decides that it would be easier to use a system of pulleys to raise the shingles. Using the pulleys, 446 N are required to lift the shingles. What is the mechanical advantage of the system of pulleys?

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

An object has a weight of 500 on earth what is the mass of this object

If the force applied to an object remains constant, is more power needed for the object to move faster ? explain