Problem 3 (20 pts) Spacemen A and B are playing catch at the opposite ends of a gigantic spacecraft, .010 m long, speeding by Earth at 0.600c to the right. Spaceman B throws the ball towards A with a velocity of 0.800c to the left (relative to himself) as in the diagram 9 0.6c 0.3c-. 5.00x10 m a) According to Spaceman A, how fast is the ball moving? b) According to Spaceman A, how long does it take for the ball to travel from B to A c) According to an observer at rest on the Earth, how fast and in what direction is the ball moving? According to an observer on Earth, how long does it take for the ball to get from A to B? d)
Solution
A) For A ball is moving with 0.8c towards left , this is same for A because A and B are in condition relative to the spacecraft.
B) Speed of light (c) = 299792458m/s
Time taken by ball ( according to A) = (5*10^9)/(0.8*299792458)
=20.847sec
C) According to observer , the speed of object =
(0.8-(-0.6))= 1.4 c ( leftward)
D) According to the observer , time taken by ball = (5*10^9)/(1.4*299792458)= 11.913 sec
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Problem 3 (20 pts) Spacemen A and B are playing catch at the opposite.docx
1. Problem 3 (20 pts) Spacemen A and B are playing catch at the opposite ends of a gigantic
spacecraft, .010 m long, speeding by Earth at 0.600c to the right. Spaceman B throws the ball
towards A with a velocity of 0.800c to the left (relative to himself) as in the diagram 9 0.6c 0.3c-.
5.00x10 m a) According to Spaceman A, how fast is the ball moving? b) According to Spaceman
A, how long does it take for the ball to travel from B to A c) According to an observer at rest on
the Earth, how fast and in what direction is the ball moving? According to an observer on Earth,
how long does it take for the ball to get from A to B? d)
Solution
A) For A ball is moving with 0.8c towards left , this is same for A because A and B are in
condition relative to the spacecraft.
B) Speed of light (c) = 299792458m/s
Time taken by ball ( according to A) = (5*10^9)/(0.8*299792458)
=20.847sec
C) According to observer , the speed of object =
(0.8-(-0.6))= 1.4 c ( leftward)
D) According to the observer , time taken by ball = (5*10^9)/(1.4*299792458)= 11.913 sec
