# Time for a micro-wave to travel a distance

1. Dec 2, 2008

### rebeccc

This is the last part of the question. I already found the frequency to be 9.7 GHz and the wavelength is .031 meters. It's just this last part of the question that I can't seem to figure out. I really don't even know where to begin, I checked my book and online and can't seem to find any relevant equations to use...

1. The problem statement, all variables and given/known data

Microwave signals are beamed between two mountaintops 54 apart. How long does it take a signal to travel from one mountaintop to the other?
My answer has to be in the units ms.
2. Relevant equations

3. The attempt at a solution

2. Dec 2, 2008

### rebeccc

Seriously, ANY ideas would be of help at this point..

3. Dec 2, 2008

### naresh

Well, you know the distance and you want the time taken to travel the distance. What else would you need to know to calculate the time?

4. Dec 2, 2008

### rebeccc

speed of the wave?

5. Dec 2, 2008

Micro waves are electromagnetic waves which travel at the speed of light in a vacuum. It sounds like you can assume this speed for this calculation.

6. Dec 2, 2008

### rebeccc

So I should divide the speed of light by 54000m?

7. Dec 2, 2008

What do you think?

Consider dimensional analysis. Do the dimensions of time fit the dimensions of distance divided by those of speed?

8. Dec 2, 2008

### rebeccc

I really don't understand what you're saying... = /

9. Dec 2, 2008

### LowlyPion

Your distance is in units of length - L.

Your basic speed of light is in units of length over time L/T.

If you divide L/T by L you would get 1/T wouldn't you?

10. Dec 2, 2008

### rebeccc

When I divided the speed of light (299,792,458 m/s) by my distance (54km or 54,000m), I got 5551.7 and this was not the correct answer. I then set my 5551.7 equal to 1/T and solved for T. By doing this I came up with 1.79 * 10^-4. This was incorrect as well. = /

11. Dec 2, 2008

### LowlyPion

The answer is looking for units of milliseconds.

12. Dec 2, 2008

### rebeccc

Ahh, genius! I converted the units and it worked! Thanks SO much!