Energy

[groovy chick]

A flywheel is rotating at high speed. No energy is being supplied to it. The flywheel is used to turn a dynamo, and the energy from the dynamo is used to light a bulb.
The bulb is left connected until the flywheel stop rotating. Not all the energy stored in the flywheel is transferred to the bulb. Some of it is lost. Give two places from which it is lost, and explain how it is lost.

[bobclean]

Heat loss at the light bulb, heat loss via friction at the flywheel axle.

[chamois]

Hang on. The sentence says "Not all the energy stored in the flywheel is transferred to the bulb". In other words, the energy is lost before the bulb.

Doesn't this mean that the heat loss at the bulb cannot be relevant as the loss is before the bulb?

[wildwood]

also, the dynamo will dissipate a fair whack of energy as heat. If you want to go absolute, even the electrical wires that carry the energy will loose a small amount.

[s10driver]

There's also air friction on the flywheel.

[dundurn]

And unless all this is happening completely silently, energy is lost as noise also

[Teddio]

The flywheel has kinetic energy. Some energy is lost due to friction in the bearings and air drag. The dynamo coils have electrical resistance so heat will be produced (Power = Current squared X Resistance).
The electrical energy supplied to the bulb from the dynamo will be converted to heat and light energy.

[kujawski]

this is a question from a 1950's science book