Energy Conservation apparatus design

How do I store the energy in the flywheel with the falling mass?

To convert Falling Mass to Kinetic energy in a fly wheel you need a conversion mechanism (which will have its own losses.) One possibility is to use a lever with a ratcheting gear on the opposite end.(as in a pedal and bicycle rear axle)

How can the flywheel's energy be converted to PE again through a spring?

It depends on the type of spring.

Regardless of the spring; if you want to see, and control each step, a ratcheting mechanism is required. From the flywheel, a simple clutch that moves a lever that compresses the spring in one direction would do. The ratchet would ensure it does not return and that all the energy of the flywheel is transferred to the spring.

To reverse the motion simply release the ratchet.

Here are a few drawings

Weight to flywheel

Flywheel to spring

Well how about a solar panel to run a small motor that would push a fly wheel or wind a spring attached to a fly wheel to a pint where it locks and when power is needed the the fly wheel could be unlocked to allow the flywheel with attached magnetic to create engry and light a blub.

or you could build one of these

http://otherpower.com/turbineplans.html

It strikes me that maybe the best way to store the flywheel energy is by means of a head of water, or a battery, charged via an alternator. In this way all the losses can be calculated easily. If you do it mechanically, friction losses and flexure will be a problem. Also your conversion to electricity is likely to be in the low 20s. A bit of friction and springiness in a linkage could wipe out most of the initial energy input.

Do the students a favour and don't show them any Tom&Jerry contraptions.

I suggest you use a much simpler example using a setup for near 100% efficiency. Otherwise the obvious losses will tend to demonstrate the opposite of what you want to impress upon the students discrediting the whole conservation concept! I.e.:

1. Just show a simple pendulum at work.

2. Or drop a hard ball on a hard surface and let it bounce.

By the way, electric to mechanical energy conservation is tricky to demonstrate (the heat dissipation is significant unless you use cryogenics!!!) and requires dedicated measurements and calculations. This beats the purpose of the demonstration, because the results won't be intuitive.

One more thing: You can't teach conservation & efficiency simultaneously. If the rig is appropriate for demonstrating conservation, then it's inappropriate for showing and understanding power loss and vice versa.

Best of luck

Mount your flywheel on a shaft with extra length. Wrap the shaft with a very flexible cord or string. Put your weight on the cord and mark the height you start at and release it. The flywheel will store the energy and then use it to wind the cord back on to the shaft. Measure how high it goes then do the math!

If you need to jazz it up, use some high-tech measuring device like an encoder attached to the shaft and use a computer to count the pulses. I know HP makes one used a lot and should be cheap, but a led/photo transistor opto-interrupter could be used with a homemade encoder disc.

Google the items and there should be plenty of instructions come back.

Good luck!

When it comes to conserving energy, I came across an article that talks about using Sharp LCD tvs that run in solar energy. That will be really economical considering the amount of energy that LCD TVs consume. Take a look at it

http://www.kanbal.com/index.php?/Electronics/sharp-carves-out-the-solar-powered-lcd-tv.html