Ans. MEASURING SPEED OF SOUND BY ECHO METHOD
Apparatus: measuring tape, stopwatch, flat wall that can produce a good echo.
Procedure
1. Use the tape to measure a distance of 50 metres from the wall.
2. Now clap your hands in front of the wall at a distance of 50 metres and check if you can clearly hear an echo from the wall. Make sure that echo is not
coming from any other wall in the area. The time taken by the sound to travel 100 metres is the time difference between the clap and the echo.
3. Now restart the clapping and start the stopwatch at the first clap. Count the number of claps, and stop the clapping and the stopwatch when you hear the echo of the 10th clap (say).
4. Now find the average time for 10 claps. After calculating the time interval t between claps and using the formula s = v t, we can calculate the speed of the sound.