14. Two space ships each measuring 100 m in its own rest frame pass by each other travelling in opposite directions. Instruments on space ship A determine that the front end of the space ship B required 5.00 x 10 s to traverse the full length of A. (a) What is the relative velocity of the two space ships? (b) A clock in the front end of B reads exactly one O'clock as it passes by the front end of A. What will the clock read as it passes by the rear end of A? (Ans. (a) 2 x 107 m/s (b) 1 + 4.99 x 106 s) 15. Life time of a particle is 2.2 x 106s in a frame in which it is at rest. Calculate the average distance it will travel in vacuo before decaying if its speed is (a) 0.9 c, (b) 099 c and (c) 0.999 c. (Ans. (a) 1.36 km; (b) 4.6 km; (c) 14.5 km) 16. What is the velocity of a metre scale if its length is observed to be shortened by a centimeter? (Ans. v = 0.141c)