A small source of sound vibrating at frequency 500Hz is rotated in a circle of radius 100/πcm at a constant angular speed of 5.0 revolutions per second. The speed of sound in air is 330m/s.
If the observer moves towards the source with a constant speed of 20m/s , along the radial line to the centre , the fractional change in the apparent frequency over the frequency that the source will have if considered at rest at the centre will be