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Solved exercise · level 3 of 5

Power of a crane motor

Skills: Calculate

Statement

A crane whose mechanical parts have an efficiency of 0.6 must lift a mass of 500 kg to 10 m in 60 s. What useful power must its motor deliver? (g = 9.81 N/kg)

m = 500 kg · h = 10 m · t = 60 s · η = 0.6

Parametric exercise: the values change with every draw; these are one example.

Guided problem in 4 steps: unknown, formula, units, data, result.

1 hint from Bastaya available in the lab
Solution

Useful work W = m·g·h = 500 × 9.81 × 10 = 49050 J; useful power 817.5 W; the motor delivers P = 817.5 / 0.6 = 1363 W.

Course sheet of the chapter : Power, energy, efficiency

This chapter is covered by the paths: General electricity, ISL-oriented exercises

Other exercises of the chapter

Simulated time00:00:00
Q = I·t-
W = P·t-

Circuit diagram CEI 60617

How does it work?

Each big hole is a circuit node: you push one leg of a component into it. The 4 small holes around it are connected to it: chips and leads plug in there.

  1. Place a component Drag it from the palette: it snaps onto the grid. R rotates it.
  2. Bridge neighbouring holes Pick the jumper chip (or C) and drag on the board: bridged holes become a single node.
  3. Draw a lead For long links and the power supply: from one big hole to another, or to a terminal.
  4. Close the loop The circuit is solved live (Ohm, Kirchhoff) and the diagram follows.

Shortcuts

Del
delete
R
rotate
C
chip brush
Esc
cancel
wheel
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fit the board
drag background
pan

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