Physics - Light and Sound

The key words -

- Sound

- Sound Waves

- Vibrations

- Echo

A object that makes a sound or something that transfers a sound in the air is called a sound wave, the process of the transformation into the ear. When the sound is created, it travels through the air and when looking at diagrams, if the wave's space is large, than the lower the pitch is, the amplitude (sound waves height), which describes the volume of the sound.

Questions based on "Sending Sounds" -

1. What are sound waves?

2. What is the height of the sound wave called? Hint - Starting with A..

3. If the sound wave's are more squished together (not spaced out) then what does that signify?

4. How does the sounds travel through the air?

5. What is the movement called? Hint - Starting with V..

DONT LOOK AT ANSWERS UNTIL AFTER QUESTIONS! -

1 - Sound waves is the process and a way of describing the movement of sound

2 - Amplitude, 3 - It signifies that the pitch of the sound is higher.

4 - By sound waves, 5 - Vibrations

Sounds need a mateiral to travel through -

- Sound waves can travel through LIQUIDS and SOLIDS, this is a common mistake, most people think that sound waves can only travel through gases, but that is incorrect.

- Examples of hearing through liquids and solids - Dolphins underwater, they can hear eachother in the sea.

- Sounds CANNOT travel through empty spaces (with no air), without air, the sounds cannot travel and there is no "squish" or "squash" of the sound waves.

- Speed of sound is 330 meters PER second.

- Sounds travel through water faster than solids and air.

- Sound is much more slower than light, light travels at 300,000 kilometers PER second, That's why you SEE a flash of lightening before you HEAR it.

Questions based on Sending Sounds + Speed of Sound -

1. What is the main speed of sound (not exact)?

2. Can gas and liquids have sound transferred into them?

3. If yes, which one is faster? Liquid, Solid or Air?

4. If you have a Vacuum pump and you **** out all the air in your bedroom, your cell phone starts ringing, would you be able to hear the ring from outside your room? Why not?

DONT LOOK AT ANSWERS UNTIL AFTER QUESTIONS -

1 - 330 meters per second, 2 - Yes they can, gas and liquids are actually better transferable items.

3 - Liquid - For instance Water, 4 - No, you would not be able to hear it because sound cannot travel out of an empty space and there are no sound waves in empty spaces.

Speed of Sound FORMULAE -

- You can use a echo to work out the speed of sound. If there is a girl, standing 330 metes FROM a wall. She fires a starting pistol, her friend hears the echo 2 seconds later. The sound has travelled a distance of 2 x 330 meters. The time taken is 2 seconds. So:

speed of sound = distance traveled = 2 x 330 = 330 m/s

time taken 2

TRICK QUESTION + Method -

If you see a flash of lightning, then hear the crash 2 seconds later, the sound arrives. Sound travels 330 meters every second, so in 3 seconds, it travels 3 x 330, or 990 meters. So the flash was 990 meters away from you.

- Dylan is standing 110 meters from a wall, if Dylan shouts -

A. What time does it take for the sound to reach the wall?

B. When will Daniel hear his echo?

C. If Daniel stands closer to the wall, how will this affect his echo?

- Assume that the speed of sound in the air is 330 m/s.

A. Give one reason for each of the following -

- You can hear sound coming from the next room, even though all the doors and windows are tightly shut.

- Sound cannot travel through vacuum.