Physics - Sound Flashcards
Sound
What happens if the air is removed from the jar using a vacuum pump?
No sound will be heard
Sound is vibrations in a medium like air or water
It cannot travel in a vacuum
sound is energy
Do light waves or sound waves travel faster in air?
Light waves travel at 300 million meters/second
Sound travels at 343 meters/second (at 20oC)
Sound is almost a million times slower than light
Why are the visual effects of fireworks a few hundred meters away seen shortly before the sound effects are heard?
Because light travels almost 1 million times faster than sound.
l_ight_: 300 million meters/second
sound: 343 meters/second
What is the speed of sound in water?
Distance sound wave travelled: 150 x 2 = 300m
Time for echo to be heard: 0.2 seconds
- speed = distance/time*
- speed = 300/0.2 = 1500 m/s*
speed of sound in water is 1,500 meters/second
What are echoes?
Reflected sound
What is echolocation?
The location of objects by relected sound
eg, used by dolphins and bats
A man fires a starting pistol, 300m away from a wall.
He hears an echo 2s later.
Calculate the speed of sound in air
dads silly triangle
- speed = distance/time*
- speed = (300 x 2)/2 = 300*
speed of sound in air is 300 meters/second
Describe, using a labelled diagram, an investigation you could carry out to show that sound requires a medium in which to travel
No sound from the jar after air is removed by a vacuum pump
Why?
Sound needs a medium/material to travel
Space is a vacuum
Describe an experiment to show sound is a form of energy
