A person lifts a bucket weighing 10 kg from a well 8 m deep in 20 seconds. How much power does

| September 26, 2021 | education

A person lifts a bucket weighing 10 kg from a well 8 m deep in 20 seconds. How much power does it develop at the same time? How long does it take for a 0.4 kW pump to cope with this work?

t1 = 20 s.

h = 8 m.

m = 10 kg.

g = 10 m / s2.

N2 = 0.4 kW = 400 W.

N1 -?

t2 -?

We will assume that the bucket is raised evenly from the well.

Let us write the power N1 according to the formula: N1 = A / t1. We express the mechanical work of lifting the bucket A by the formula: A = m * g * h.

N1 = m * g * h / t1.

N1 = 10 kg * 10 m / s2 * 8 m / 20 s = 40 W.

We express the pump power N2 by a similar formula: N2 = m * g * h / t2.

t2 = m * g * h / N2.

t2 = 10 kg * 10 m / s2 * 8 m / 400 W = 2 s.

Answer: a person develops a power of N1 = 40 W, the pump will lift the load in time t2 = 2 s.



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