Chapter 15, Problem 88A

To determine

To graph: a frequency versus time graph when the car approaches and the moves away from the detector.

Explanation of Solution

Introduction:

The frequency of sound perceived by a detector is more than that of the source when the source is moving towards the detector and less when the source is moving away from the detector.

The frequency of car horn is $300\text{ Hz}$ when it is stationary.

As per Doppler effect, the frequency of sound perceived by a detector is more than that of the source when the source is moving towards the detector and less when the source is moving away from the detector.

So the frequency perceived by the detector first increase as the car is moving towards it and then decrease as it moves away from it.

So graphically, frequency-time relation can be shown as

Conclusion:

When thermal energy is transferred from a warmer object to a colder object, the two do not have the same temperature changes.