A man is lifting a piano that weighs 800 N through a distance of 10 meters using a pulley system. The man pulls the rope a total distance of 100m. What force does the man need to apply to the rope?

The force the man applied is 80 N

Explanation:

weight of the load, L = 800 N

distance traveled by the load, a = 10 m

distance traveled by the effort, b = 100 m

Output work = load x distance moved by the load

Output work = 800 x 10 = 8000 J

Input work = Effort x distance moved by effort

Input work = Effort x 100 m

Assuming an ideal machine; no friction effect, the input work will be equal to output work.

Effort x 100 m = 8000 J

Effort = 8000 / 100

Effort = 80 N

Therefore, the force the man applied is 80 N

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