An airplane travels at a constant speed $v$ for a distance

of $3000km$ as measured by a stationary observer. The

pilot measures the flight time to be $t$ and the station$-$

ary observer measures the flight time to be $t^{\text{'}}.($a$)$

Which time interval is longer? $($b$)$ If $|t-t^{\text{'}}|=4ns,$

determine the speed of the airplane. $($Time dilation

has been directly measured using atomic clocks flown

on commercial airplanes.$)$