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Solved exercise · level 3 of 5

Lifting time

Skills: Calculate

Statement

A crane whose mechanical parts have an efficiency of 0.7 has a motor with a useful power of 4204 W. How long does it take to lift a mass of 600 kg to 10 m?

P = 4204 W · η = 0.7 · m = 600 kg · h = 10 m

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 lifting power: η × P = 0.7 × 4204 = 2943 W; W = m·g·h = 58860 J; t = W / Pu = 20 s.

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

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R
rotate
C
chip brush
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