# Special relativity question, NEED HELP

Hey guys im doing special relativity in my physics class and we are working on time dilation. Right now im really confused by what my teacher said and what the book says. Can someone help me out? here is my question....

Your friend flies from Los Angeles to New York. She carries an accurate stopwatch with her to measure the flight time. You and your assistants on the ground measure the flight time as well.

a. Identify the two events associated with this measurement.
b. Who, if anyone, measures the proper time?
c. Who, if anyone, measure the shorter flight time?

I am so confused by this, please help me

## Answers and Replies

Andrew Mason
Science Advisor
Homework Helper
Hey guys im doing special relativity in my physics class and we are working on time dilation. Right now im really confused by what my teacher said and what the book says. Can someone help me out? here is my question....

Your friend flies from Los Angeles to New York. She carries an accurate stopwatch with her to measure the flight time. You and your assistants on the ground measure the flight time as well.

a. Identify the two events associated with this measurement.
b. Who, if anyone, measures the proper time?
c. Who, if anyone, measure the shorter flight time?

I am so confused by this, please help me
In a. the question is asking for the two events that determine the flight time. An event is a point in space and time. A measurement of space-time requires finding the displacement in space and in time between two events.

So what are the two events in each frame of reference (either the traveler or the person on the ground) the difference in the time co-ordinates of which is the measure the time of flight?.

In b., proper time is the time in the frame of reference of the inertial observer. Hint: in this case, is the traveler always an inertial observer?

In c., the question asks about time dilation. Observers in two different inertial frames will measure time differently.

AM