Waves

Consider the Doppler effect in two cases. In the first case, an observer moves towards a stationary source of sound with a speed of \(50 \mathrm{~m} / \mathrm{s}\). In the second case, the observer is at rest and the source moves towards the observer with the same speed of \(50 \mathrm{~m} / \mathrm{s}\). Then the frequency heard by the observer will be

[velocity of sound in air \(=330 \mathrm{~m} / \mathrm{s}\).]