Elec Class

learn electricity hands-on
0 1 / 20

Solved exercise · level 2 of 5

Useful energy of a motor

Skills: Calculate

Statement

An electric motor absorbs a total power of 1000 W with an efficiency of 0.8. How much mechanical energy is available in 15 min? Answer in kJ.

Pa = 1000 W · η = 0.8 · t = 15 min

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

Pu = η × Pa = 0.8 × 1000 W; W = Pu × t = Pu × 15 × 60 = 720 kJ.

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
zoom
0
fit the board
drag background
pan

Confirmer

Renommer

Importer un montage

Export