An ambulance is moving along a straight road at a speed of $30.0\,\text{m s}^{-1}$. The siren on the ambulance produces sound with a frequency of $2000\,\text{Hz}$. The speed of sound in air is $340\,\text{m s}^{-1}$. As the ambulance goes past a man who is standing at the roadside, what frequency does he hear while the ambulance is approaching him, and what frequency does he hear while it is moving away from him?
- Atowards: $1820\,\text{Hz}$, away: $2180\,\text{Hz}$
- Btowards: $1840\,\text{Hz}$, away: $2190\,\text{Hz}$
- Ctowards: $2180\,\text{Hz}$, away: $1820\,\text{Hz}$
- Dtowards: $2190\,\text{Hz}$, away: $1840\,\text{Hz}$