# Examples for gravitational time dilation

1. Apr 3, 2013

### Ahmed Samra

Can you tell me examples for the gravitational time dilation and its answers?

2. Apr 3, 2013

### phinds

Look up the Global Positioning Satellite System (GPS). If gravitational time dilation were not well understood, the GPS system would have you driving your car into buildings and in corn fields and rivers.

3. Apr 3, 2013

### Ahmed Samra

I understood the gravitational time dilation but I can't understand it's equation. Can you explain the equation to me?

4. Apr 3, 2013

### Ahmed Samra

I mean to tell me it's units and what do they mean

5. Apr 3, 2013

### Ahmed Samra

Can you explain to me the equation about the non - rotating sphere and when do I use it

6. Apr 3, 2013

7. Apr 3, 2013

### Agerhell

In a spherically symmetric gravitational field, where the clock has no motion at all in relation to the field, the amount of time passed as measured with the clock will vary with the factor:

$$\sqrt{1-\frac{2GM}{rc^2}}$$

So the deeper in a gravitational field you are, the more your clock will slow down. Was that what you wanted to know?

8. Apr 3, 2013

### Ahmed Samra

So, by this equation I will figure out the gravitational time dilation?

9. Apr 3, 2013

### Agerhell

Yes. You can plug in the mass of the earth and different radial distances from the centre of the earth and see how much time slows down at that position compared to if the earth had not been present.

10. Apr 3, 2013

### Ahmed Samra

Okay thank you it helped :)

11. Apr 3, 2013

### Ahmed Samra

12. Apr 3, 2013

### 1977ub

Is there a particular scenario you are trying to understand?

13. Apr 3, 2013

### Ahmed Samra

I just want to know is this the right equation for calculating the gravitational time dilation

14. Apr 3, 2013

### Staff: Mentor

yes, that is the correct equation for a spherically symmetric non-rotating mass.

please please please stop repeat-posting - it doesn't get you any faster answers and it clutters up the forum, and it makes work for the (underappreciated, overworked, infinitely patient) moderators who have to clean u the mess.

Post one single question as clearly as possible, then shut up and wait until you get either an answer or a request for clarification.

15. Apr 3, 2013

### Ahmed Samra

If I am traveling in a plane by a velocity 15000 km/s according to special relativity the time will delay for the reference frame of the observer at the sea level. So, let's say time decreased by 7 ns. However, according to general relativity time will speed up because I am away from the centre of gravity, so time will speed up according to the reference frame of the observer at the sea level, and let's say that time will peed up about 47 ns. 47-7=40 ns. So, the time will increase about 40 ns am i right?