# Acceleration and Gravity

1. Jun 26, 2014

What is the difference between acceleration and gravity?
Are they same?

2. Jun 26, 2014

### Simon Bridge

According to Newton, gravity is a force that gives rise to acceleration.

Einstein points out that you cannot, locally, distinguish uniform acceleration from gravity.

Certainly you can have acceleration without gravity - so, while gravity may thought of as an acceleration, not all accelerations are gravity.

Are you are thinking of spinning a space station to simulate gravity?
That is different from gravity.

3. Jun 26, 2014

What kind of acceleration is different from Gravitation?

4. Jun 26, 2014

### Simon Bridge

Any acceleration that is not gravity of course.
The acceleration of a car on a level road is not gravity.
The acceleration from spinning in a circle is not gravity.

5. Jun 26, 2014

6. Jul 3, 2014

So can anyone briefly explain me whats the equivalence Principle?

7. Jul 3, 2014

How is gravity different with acceleration, if both produce the same effect?

8. Jul 3, 2014

### A.T.

9. Jul 3, 2014

10. Jul 3, 2014

### stevendaryl

Staff Emeritus
If you are in a small room sitting on the surface of a planet, you notice that if you drop an object, it falls to the floor with a characteristic acceleration. This characteristic acceleration is the same for all objects--whether it's made of steel or plastic or whatever. (This is only literally true if you ignore wind resistance, of course.)

If instead of a room sitting on a planet, you're in a room on board an accelerating rocket, you notice exactly the same behavior in dropped objects.

Now, there really is a detectable difference if you perform very careful measurements. Gravity on the surface of a planet decreases as you get farther from the center of the planet according to the inverse-square law (if you are twice as far from the center, the gravity is 1/4 as strong). The fake gravity on board an accelerating rocket doesn't have that kind of drop-off.

Roughly speaking, the equivalence principle says that the ONLY difference between these two cases (on a planet vs. on an accelerating rocket) is the variation of the acceleration with location. So to the extent that your room is small enough that you can't detect differences in gravity within the room, you won't find any differences between the two cases.

11. Jul 3, 2014

### davenn

Please do some of your own study .... we are not going to spoonfeed you

Dave

12. Jul 3, 2014

### micromass

That's quite an effort you ask of us. You know we are all unpaid volunteers right? Why would we make such an effort for you if you can't make the effort of reading wikipedia or other sources?

You have asked in this thread many basic questions that you could probably have found yourself if you searched for a while.