A train whistle is sounded away from two workers

PHYSICS · Single correct · GCSE · Physics · Waves · Waves

Problem

A train whistle is sounded

4000\,\text{m}

away from two workers. Worker P places his ear on the rail, while worker Q stands beside the track in air. Worker P hears the whistle

7.0\,\text{s}

before worker Q. If the speed of sound in air is

340\,\text{m/s}

, what is the approximate speed of sound along the steel rail? (a)

570\,\text{m/s}

(b)

840\,\text{m/s}

(c)

340\,\text{m/s}

(d)

630\,\text{m/s}