Physicsmedium · Past Paper
What is the minimum distance required between a source and a reflector to hear a distinct echo in air at 20 degrees Celsius?
A1.7 meters
B17.2 meters
C34.4 meters
D172 meters
✓ Correct Answer: B — 17.2 meters
To hear an echo, the sound must travel to the reflector and back in at least 0.1 seconds, which requires a minimum distance of about 17.2 meters at standard speed.
Share this question
More from Physics
- Two objects of different masses falling freely in vacuum:
- When an object is immersed in a liquid, its apparent weight is:
- The magnifying power of a telescope can be increased by:
- A man carries a 5 kg load on his head and moves 10 m along a horizontal path. The work done by him against gravity is:
- If the mass of an object is doubled and its velocity is halved, what happens to its kinetic energy?