Joshua placed a playing card in a bicycle wheel so that the spokes would cause the car to vibrate. When he rode the bicycle fast, a high-pitched sound was produced, and when he rode the bicycle slowly, a low-pitched sound was produced. Which statement best explains why both high-pitched and low-pitched sounds were produced?

that would be b i just took the test : )

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it