What load should be applied to the free end of the rope in order to evenly lift a 10 kg

What load should be applied to the free end of the rope in order to evenly lift a 10 kg load with the help of a stationary block if the efficiency is 80%?

To find out the weight of the load that must be applied to the free end, we use the formula (we take into account that for a fixed block it is true: h (lifting the load) = s (moving the end of the rope)): η = ΔErg / Azatr = mg * g * h / ( F * s) = mg * g / Pg, whence we express: Pg = mg * g / η.

Const: g – acceleration due to gravity (g ≈ 10 m / s2).

Data: mg – weight of the cargo (mg = 10 kg); η – unit efficiency (η = 80% = 0.8).

Let’s calculate: Pg = mg * g / η = 10 * 10 / 0.8 = 125 N.

Answer: The weight attached to the free end must have a weight of 125 N.

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