Simple machines

Hi, here are some videos on simple machines. Some of the terms used in the videos can be unfamiliar to you but dun worry, you just need to know the concept behind the simple machines.

Inclined plane: http://www.youtube.com/watch?v=pG_kT565-XQ&feature=related
Lever: http://www.youtube.com/watch?v=wV1pYkTtsxg&feature=related
Pulley: http://www.youtube.com/watch?v=TlPWy7qW7oM&feature=related

Harmful natural forces

Hello!

Here are some links to show the destruction of natural forces. You can see how a tornado, tsunami, earthquake and volcanic eruption can cause great devasation.

Any good links to share for the harmful natural forces?

Tornado: http://www.youtube.com/watch?v=43VoMesUd2Q
Tsunami: http://www.youtube.com/watch?v=w9ygYqj4rVM
Earthquake: http://www.youtube.com/watch?v=4Y-62Ti5_6s
volcanic eruption: http://www.youtube.com/watch?v=Q4MSt6PmPHc