Farhan, standing 17.25 m from a wall, hears an echo on a winter day at 10°C but not on a summer day at 30°C. The reason

Question

Farhan, standing 17.25 m from a wall, hears an echo on a winter day at 10°C but not on a summer day at 30°C. The reason is

Accepted Answer

winter $v \approx 338$ m/s gives round-trip $\approx 0.102$ s ($\geq 0.1$ s); summer $v \approx 349.84$ m/s gives $\approx 0.0986$ s ($< 0.1$ s), so the echo is not heard

Answer

summer is warmer so sound is fully absorbed

Answer

echo only happens at low pressure

Answer

echo only happens in summer