Sound waves are mechanical waves while electromagnetic waves are not. Thus, sound waves require a medium for propagation while electromagnetic waves do not. Sound waves are produced by mechanical vibrations and propagate through liquid, air and plasma as longitudinal waves. While electromagnetic waves are <span>produced by </span>accelerating or decelerating<span> charged particles. It also contain a</span> <span>magnetic field. Because they are not mechanical waves, it can propagate through a vacuum as well as air, liquid, and solid.</span>
Answer:

Explanation:
Since, Alex is at rest. Therefore, the speed measured by him will be the absolute speed of car P. Therefore, taking easterly direction as positive:
And the absolute velocity of Barbara's Car is given as:
Now, for the velocity of Car p with respect to the velocity of Barbara's Car can be given s follows:


Answer:
I think the right answer is option B.