What are the factors that affect the speed of sound in gases?

a) What do you understand by the term ‘ultrasonic vibration’?
b) State three uses of ultrasonic vibrations.
c) Name three animals which can hear ultrasonic vibrations.

Suppose that a sound wave and a light wave have the same frequency, then which one has a longer wavelength?
a) Sound
b) Light
c) both a and b
d) data not sufficient.

A source producing a sound of frequency 90 Hz is approaching a stationary listener with a speed equal to (1/10) of the speed of sound. What will be the frequency heard by the listener?

A source of sound is moving with a velocity of 50 m s^–1 towards a stationary listener. The listener measures the frequency of the source as 1000 Hz. what will be the apparent frequency of the source when it is moving away from the listener after crossing him? (velocity of sound in the medium is 330 m s^–1)