You stand by the railroad tracks as a train passes by. you hear a 1 000-hz frequency when the train approaches, which changes to 800 hz as it goes away. how fast is the train moving? the speed of sound in air is 340 m/s.

Explanation:

As per Doppler's effect when source and observer moves relative to each other then the frequency of the sound observed is different from the real frequency

When source is moving towards the stationary observer then we have

now when source of sound moving away from stationary observer then we have

now from above two equations

here we know that

v = 340 m/s

now we have

6 cos 34, 6 sin 34 trig

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.