Which of the following is true about high-energy mechanical devices?
a. they usually need to be kept warm in order to preserve mechanical energy.
b. they usually need to be cooled to dissipate thermal energy build-up and prevent damage.
c. they usually convert radiant energy into electrical energy.
d. during an energy conversion, none of the energy is transferred as thermal energy because the devices are free of friction.

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.

their crystal patterns have been disrupted by stress

grav force prop 1/r squared 2r all squared is 4rsquared 1/4rsquared quartered