Sunday, 30 January 2011
For whom does the bell toll?
Can you make the bell stop ringing without touching it?
Press the button for the bell inside the dome. Then, suck the air out of the dome by pressing the green button, and ring the bell again. You can return the air to the dome by pressing the red button.
When the dome is filled with air, the sound of the bell can be heard quite clearly. As the amount of air decreases, the sound becomes muffled and eventually inaudible.
Sound is a mechanical wave motion that requires a medium in order for it to travel. The source of the sound makes the air molecules vibrate and the vibration is further transferred through the molecules to your ears. Sound cannot travel or be heard in a vacuum, because there are no particles in a vacuum to transfer the sound.
In space films, there are sometimes battle scenes in which the characters are shooting with laser guns. The laser beams flash back and forth and the din of the battle is deafening. These scenes are made in accordance with the laws of drama rather than the laws of physics. There is no air in outer space, so the beams of the lasers would not be visible from the side; air molecules are required in order for the beam to scatter to the sides. As there is no medium to transfer the sound either, the battle would, in reality, be completely silent.