Why does water pass through a sieve?
Is it possible to create a machine that will run forever?
Why is air a poor conductor of heat?
Why do bicycle wheels have spokes?
What is time?
Why can’t we totally eliminate friction on earth?
Where does electricity come from?
Why does fan (wings) rotates in clock wise direction?
Is there a universal positive energy as well as a universal negitive energy?
What is sound?