As a train approaches a platform

PHYSICS · Single correct · CBSE · Physics · Waves · Waves

Problem

As a train approaches a platform, a passenger standing on the platform hears the train’s horn at

800\,\text{Hz}

. After the train passes and moves directly away, the passenger hears the horn at

680\,\text{Hz}

. Take the speed of sound to be

340\,\text{m}\!\cdot\!\text{s}^{-1}

. What is the train’s speed relative to the ground? (a)

55\,\text{m}\!\cdot\!\text{s}^{-1}

(b)

28\,\text{m}\!\cdot\!\text{s}^{-1}

(c)

60\,\text{m}\!\cdot\!\text{s}^{-1}

(d)

30\,\text{m}\!\cdot\!\text{s}^{-1}