A spring is stretched from rest and released. Which of the following describes the frequency of the spring?
A:the speed of the spring as it passes through the equilibrium position
B: the number of times the spring moves up and down in 1 second
C:the time it takes the spring to compress and then expand once
D: the number of coils on the spring

Explanation:

you have given two questions which one to answer

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.