How and why planets orbit the sun and how and why a planets speed changes orbit

The details are very long and complicated. The simplest way I can answer those 4 questions is: That's the way gravity works.

If you take Newton's law of gravity and his three laws of motion, and massage them properly using some geometry and some calculus, you can show that planets MUST move like Kepler's laws say they do, and like what we see them actually doing in the sky.

(I used to be able to do this, but it's been a while.)

the temperature in kelvin of 2.0 dm3 of an ideal gas is doubled and its pressure is increased by a factor of four. what is the final volume of the gas

i already answered it by 34/s