Physics Questions

[Futuremed92]

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Imagine that you are in an inertial frame in empty space with a clock, a telescope, and a powerful strobe light. A friend is sitting in the same frame at a very large (unknown) distance from your clock. At precisely 12:00:00 noon according to your clock, you set off the strobe lamp. Precisely 32.0 s later, you see in your telescope the face of your friend’s clock illuminated by your strobe flash.

How far away is your friend from you in seconds?

How far away from you is your friend in millions of km?

What should you see on the face of your friend’s clock if that clock is synchronized with yours?

 

[anon4895]

Imagine that you are in an inertial frame in empty space with a clock, a telescope, and a powerful strobe light. A friend is sitting in the same frame at a very large (unknown) distance from your clock. At precisely 12:00:00 noon according to your clock, you set off the strobe lamp. Precisely 32.0 s later, you see in your telescope the face of your friend's clock illuminated by your strobe flash.

How far away is your friend from you in seconds?

How far away from you is your friend in millions of km?

What should you see on the face of your friend's clock if that clock is synchronized with yours?

So you're both in the same inertial frame of reference. Basically that just means both of you aren't moving. 32 seconds round trip means the light spends 16 seconds getting there and then 16 seconds getting back.

The distance between you, s, is equal to ct where c is the speed of light and t is the time.

s = 16c so 16c is the distance between you in meters if c is in m/s

Your friends clock should read 16 seconds after 12 when you see it.

 

[Futuremed92]

Thanks! I had one additional question

Clock P is at rest alongside a racetrack. A jockey on horseback checks her watch against clock P as she passes it during the first lap (call this event A) and then checks her watch again as she passes clock P the second time (call this event B).

(a) Which clock (clock P or the watch) measures the spacetime interval between events A and B?

(b) Which measures proper time?

(c) Do either of the clocks measure coordinate time between the events in the ground frame?

Thank you so much in advance!

 

[dontbeanegaton]

a) the watch
b) P; the reference frame is the place where the two events are in the same spatial but not temporal location, and the proper time is measured there
c) don't think so; the coordinate time has to be measured by a distant observer
I really don't think this is MCAT material...