5.3 Exercise 3

b. Spacecraft A and B pass in opposite directions at a relative speed of $4.00 \times 10^{7} \text{m}/\text{s} .$ An internal clock in spacecraft A causes it to emit a radio signal for 1.00 s. The computer in spacecraft B corrects for the beginning and end of the signal having traveled different distances, to calculate the time interval during which ship A was emitting the signal. What is the time interval that the computer in spacecraft B calculates?