# Homework Help: I'm having trouble with horizontal line problems and I'd love some help

1. Sep 15, 2011

### ColleenaMarie

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

During an Apollo moon landing, reflecting panels were placed on the moon. *This allowed earth-based astronomers to shoot laser beams at the moon's surface to determine its distance. *The reflected laser beam was observed 2.52 s after the laser pulse was sent. *What was the distance between the astronomers and the moon?

2. Relevant equations
D=rt

3. The attempt at a solution
How do you find the rate with just time??

2. Sep 15, 2011

### Gordanier

Well you are given time, which is equal to 2.52 seconds. The distance is what you are trying to figure out, and I assume that "r" represents the speed of light? So "r" is a constant which you should be able to look up in your textbook if you do not know it.

Then you just fill in what you know to get D, and remember, the laser is going to the moon and back, so it is travelling twice the distance from just the astronomer to the moon.

Cheers

3. Sep 15, 2011

Thank you!