Waves Questions

A motor cycle starts from rest and accelerates along a straight path at $2{\text{m/s}}^2$. At the starting point of the motor cycle there is a stationary electric siren. How far has the motor cycle gone when the driver hears the frequency of the siren at $94\%$ of its value when the motor cycle was at rest? (speed of sound $=330{\text{m s}}^{-1}$).

Three sound waves of equal amplitudes have frequencies $(\nu -1)$, $\nu$, $(\nu +1)$. They superpose to give beats. The number of beats produced per second will be: