Posted by gayathri on .
Can you please help me with this question?
A person is flying through space with person B exactly 186000 miles behind. When person A wants to accelerate, he uses a flashlight to signal person B.This means they accelerate together and remain exactly 186000miles apart. Person A wants exactly 1 sec to allow light to reach Person B before he accelerates, so they remains 186000 miles apart from their perspective. What observation will a person standing on ground make?

physics 
drwls,
If there is the required 1 s delay by person A, then they accelerate together. A person on the ground sees the same thing.
The distance between A and B may be slighly less than 186,000 miles, seen from the ground, depending upon the speed and direction of motion. The measured 1 second delay by A may also be shorter.