1

General Science / Electromagnetic waves

« on: 21/09/2010 15:41:05 »

When we heat a metal, the positive kernels begins to vibrate. will this vibrations produce electromagnetic waves ?

2

Physics, Astronomy & Cosmology / How can we accelerate in space

« on: 21/09/2010 14:52:09 »

Imagine we are in a space craft which is moving with a constant velocity in empty space. If we are not influenced by any gravitational forces, and if we restart the engine, will it be accelerated ,Why?

3

Physics, Astronomy & Cosmology / What are "energy" and "work" ?

« on: 30/08/2010 16:23:08 »

I can't get the actual concept or meaning of various forms of energies . Actually what is energy ? My textbook defines energy as capacity to do work.Most of the websites define energy in the same way. But i can't understand any thing from that definition. I also want to know what is work.
Actually, why do we need these quantities?

Thanks in advance.

[MOD EDIT - PLEASE PHRASE YOUR POST TITLES AS QUESTIONS. THANKS. CHRIS]