Which two processes can generate energy to a star or gas cloud maintain its internal thermal pressure?

A star is born when the material of a nebula collapses due to the gravitational force of its elements. Converting this later into the nucleus of the new star, composed of hydrogen.

Then,  when this nucleus has reached sufficiently high density and temperature, it becomes helium by means of nuclear fusion (union of two light atoms), releasing energy in the process, which is the cause of the great luminosity of the star.

In other words, stars generate their own energy, in a process in which there is a balance between the gravitational pressure that compresses (contracts) matter and raises its temperature sufficiently for nuclear reactions to start, generating pressure in the opposite direction to the gravitational force by the heat produced in the reaction.

So, these nuclear reactions expand the star for most of its life, as long as this equilibrium exists.

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.

answer: i'm not sure which is which for i get confused on it all the time but i can tell you that the answer lies with the convex and concave devices. i hope this you. have a good day and best of luck to you!

explanation: