# Using a stationary block, a load weighing 100 kg is lifted to a height of 1.5 m.

Using a stationary block, a load weighing 100 kg is lifted to a height of 1.5 m. Determine the work done in this case if the efficiency of the block is 90%

Problem data: m (weight of the load lifted with a fixed block) = 100 kg; h (required lifting height) = 1.5 m; η (efficiency of the fixed unit) = 90% (0.9).

Reference values: g (acceleration due to gravity) ≈ 10 m / s2.

We express the work perfect when lifting a load from the formula: η = Ap / A = ΔEp / A = m * g * h / A, whence A = m * g * h / η.

Calculation: A = 100 * 10 * 1.5 / 0.9 = 1667 J.

Answer: When lifting a load weighing 100 kg, work was done in 1667 J.

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