A person travelling by a car moving at 100 km h–1 finds that his wristwatch agrees with the clock on a tower A. By what amount will his wristwatch lag or lead the clock on another tower B, 1000 km (in the earth’s frame) from the tower A when the car reaches there?
Time taken by the car to reach the tower B from tower A =
.
As the frame of wrist watch is moving 
the wrist watch will lag by 
Where 
, V is velocity of moving object and C is speed of light in vacuum i.e. 
And 
is time in rest frame .
V=
as 
using binomial expansion we know we can write
when 
Similarly, 
=
And as we can see the calculated value is too small to make drastic affect that’s why we don’t face any trouble in real life situation.
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