Physics for IGCSE & O level - Waves And Sounds (Section 1 - No. 17)
If you clap your hands and hear an echo 1 second later, how far away is the reflecting surface (assuming the speed of sound is 340 m/s)?
170 meters
340 meters
680 meters
100 meters
Giải thích
The sound traveled to the surface and back, covering the distance twice. Distance = (340 m/s * 1 s) / 2 = 170 meters.