In this activity you will discover if the sound can be transmitted in empty space

• You will need a device from which the air can be removed and a timer.

• First set up the time to ring in a minute. Put the timer inside the device and let the minute pass. Do you hear the ring? .

• Now remove the air from the device and put again the timer inside the device. Wait till the minute passes. Do you hear the ringing?

​

​Activity No 1

Does the speed of sound depend on the temperature of the propagation medium?

1. Open the simulation: https://www.seilias.gr/images/stories/html5/soundSpeed.html

2. First calculate the speed of sound for the air temperature of 5°C:

•   Set the temperature at 5°C.

• Press the button Μέτρηση.   

• A laptop with two microphones will appear. You can move the microphones to change the distance between them. Set the distance between them to Δx=5m. When you press start, a wave sound is propagating. When it reaches the first microphone the time t₁ is appeared on the laptop’s screen. This is the time needed for the sound to reach the first microphone. When the sound reaches the second microphone the time t₂ is appeared on the laptop’s screen. This is the time needed for the sound to reach the second microphone.

3. With the same way calculate the speed of sound for the air temperature of 20°C and 40°C:

Activity No 2