It is because of the nuclear fusion reactions which power the Sun. They produce energy by converting hydrogen into helium. In fact it's more complicated than the question suggests, but that's the basic idea.
Yes, all stars run on a limited suppliy of fuel - mainly hydrogen. Some stars burn it very quickly but reach high temperatures, while other lower mass stars burn their fuel more slowly, lasting for longer, but burn at cooler temperatures.
Yes, stars have cores where nuclear fusion reactions occur. This is where the immense pressure and temperature allow hydrogen atoms to fuse into helium, releasing energy in the form of light and heat. The core is the hottest and densest part of a star.
Faster than on Earth? The reason it falls slowly on Earth is because of air resistance. You can also make it fall quickly on Earth if you make it fall within a vacuum chamber.
The Sun is currently in the main sequence phase of its life cycle, where it fuses hydrogen into helium in its core. Eventually, it will exhaust its hydrogen fuel and expand into a red giant, shedding its outer layers to form a planetary nebula. Finally, it will collapse into a white dwarf, slowly cooling down over billions of years.
Slowly.
slowly
slowly
slowly
The opposite of quickly is... slowly.
Because ftw
Slowly by cellular respiration, quickly by combustion (burning).
slowly
slowly
Slowly
slowly
Rapidly