Vibration Pump Wave
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Vibration Pump Wave
Sound waves questions for physics - Please reply as soon as possible?
1) What type of wave is a sound wave?
2) What property of waves causes echoes?
3) Which of the following frequencies would you be able to count the vibrations of without special instruments? : 2Hz, 20Hz, 200Hz, 2000Hz, 2kHz, 20kHz
4) Why can sound from a bell can often still be heard when the vacuum pump has removed all of the air that it can from a bell jar?
Thanks in advance!! 
1 & 2 are answered.
3. How fast can you count? With a struggle I could count about 2 cycles per second, but no higher. In terms of sound only 20KHz is in the audible range.
4. If you can hear the bell it is either because all the air has not been removed, or because the vibrations can travel along whatever is being used to support the bell. If the experiment is done properly, with no support for the bell able to transmit the vibrations to the bell jar, you will not hear it ringing when the air has been removed.
Black Box - Strike it up (DJ Lelewel mix)