Question

Some homes have stairs that are too steep or narrow for moving large pieces of furniture. In such cases, furniture may be lift ed by pulleys and moved in through upper windows. What is the efficiency of a system that uses 280 N of force to lift a 100 kg bed 6 m to an upper window? Those working the system have to pull 24 m of rope to lift the bed.

Answer 1

The efficiency of the system is 89.3%

Step-by-step explanation:

Efficiency of a machine is defined as the ratio of useful work done by a machine to the total work put into the machine.

Mathematically, efficiency = (work output/work input) * 100%

work output = load * load distance

where load = 100 kg * 10 m/s² = 1000 N; load distance = 6m

work output = 1000 * 6 = 6000 J

work input = effort * effort distance

where effort = 280 N, effort distance = 24 m

work input = 280 * 24 = 6720 J

Efficiency = (6000/6720) * 100%

Efficiency = 89.3%

Therefore, the efficiency of the system is 89.3%