# How Can I Calculate My Target's Distance?

1. Sep 9, 2010

### BeginnerPal

I find applicable physics that we can experiment practically is very interesting.

Assume i'm in a flat landscape, far away there is a small building. How can i know the distance to that small building from where i stand? I need a practical achievable solution...

My first suggestion is:

1. Drive a car at a certain fixed speed from the starting point lets say the speed is 40 km/h to the end/target location.

2. We have to track the time from starting point to the end point.

3. By the time we reach the end point. We apply the following formula:
Distance = Velocity/Time ... Obviously unit conversion has to be involved in
someway or another.

My second suggestion is:

Use a good laser range finder.

The distance doesn't have to be perfectly accurate. Are my suggestions O.K? Do you have
any other ideas?

Thanks

Last edited: Sep 9, 2010
2. Sep 9, 2010

Triangulate.

3. Sep 9, 2010

### skeptic2

Do you know the height of the building?

4. Sep 9, 2010

5. Sep 9, 2010

### skeptic2

Topographical map that shows the building?

6. Sep 9, 2010

### skeptic2

A parallax rangefinder?

7. Sep 9, 2010

### skeptic2

Knowing the focal length of the camera's telephoto lens (exactly), calculate from the size of the image on the film.

8. Sep 9, 2010

### Redbelly98

Staff Emeritus
If you're going to drive a car to the building, just use the odometer. Forget about maintaining a known, uniform speed and measuring the time.

9. Sep 9, 2010

### Staff: Mentor

Use mirror flashing Morse code with someone in the building, to have them relay their GPS coordinates to you, and subtract from yours.

10. Sep 9, 2010

### BeginnerPal

Good solutions. For those who asked the height of the building, height is not known just assume the location is place where boundary lines was drawn in square to represent the building virtually. Thanks for all of your responses.