The amplitude of a compressional wave depends on the

a.) density of material in compressions and rarefactions
b.) distance between crests and troughs
c.) number of wavelengths that pass by a point each second
d.) vibration of electric and magnetic parts

Volume of a sound wave  which is a type of compressional wave  is the description of amplitude. The amplitude is a measure in the intensity of the waves, or the amount of variation in air pressure. Our perception of pitch varies with the frequency, or how frequently the alternations in air pressure persist. The answer is A.

Answertraveling around a circular trackexplanation"traveling around a circular track" is the best answer as you could be traveling around a circular track at a constant speed. your velocity would therefore have the same magnitude but will always be constantly direction. since acceleration is the rate of change of velocity, the rate of change will only involve the direction of velocity and not the magnitude.wrong choices: "an object at rest" does not accelerate at all"increasing speed while traveling around a curve" means that the acceleration will not be constant due to only change in direction; it will be constant due to both magnitude and direction"an object in free fall" does not necessarily change direction