Homework Help: Physics repost

Posted by Mary on Wednesday, October 17, 2007 at 10:04am.

I apologise for reposting this question but it is still not working out for me.

I know that:

speed of light c=3.0x10^8
Time interval delta t=0.19x10^-9s

The relationship between actual time and roudtrip distance is

d=ct

Also if there is and uncertainty of delta time, then it introduces an uncertainty of delta distance

ie d+delta d = c(t + delta t)

Knowing all of this I still don't understand how to work out the problem. I am continuosly coming up with the incorrect answer. please help!

Question:
The distance between earth and the moon can be determined from the time it takes for a laser beam to travel from earth to a reflector on the moon and back. If the round-trip time can be measured to an accuracy of 0.19 of a nanosecond (1 ns = 10-9 s), what is the corresponding error in the earth-moon distance?

Physics repost - drwls, Wednesday, October 17, 2007 at 10:13am
The Earth moon distance is d, and the round-trip travel time is
t = 2 d/ c
d = (c/2) t

delta d = 1.5*10^8 m/s * (delta t)
= 0.19*10^-9 s *(1.5*10^8 m/s) = 2.9*10^-2 m = 2.9 cm
(about one inch)

Answer this Question

Related Questions

physics - An interstellar ship has a mass of 1.20 X10^6 kg and is initially at ...
physics - An interstellar ship has a mass of 1.20 X10^6 kg and is initially at ...
Physics - When you approach a blinking source of light, the frequency of its ...
Physics Help me Someone plz - If a galaxy is traveling away from us at 2.0% of ...
Physics Plz help me - If a galaxy is traveling away from us at 2.0% of the speed...
To Lynn,Alex,Physics_student,Natasha - Please refrain from reposting the same ...
repost math question - An aircraft flew 6 hours with the wind. The return trip ...
physics - Suppose the time taken for light to bounce to and fro between the ...
Physics - A stroboscope is a light that flashes on and off at a constant rate. ...
physics - Use the fack that the speed of light in a vacuum is about 3.00x1000 m/...

For Further Reading

First Name:
School Subject:
Answer: