A spacecraft (Lo = 80 m) travels past a space station at speed 0.7c. Its radio receiver is on the tip of its nose. The space station sends a radio signal the instant the tail of the spacecraft passes the space station. (a) What is the length of the spacecraft in the reference frame of the space station? L=80(1-.7^2)^.5 = 57m (fine) (b) What is the time taken for the radio signal to reach the nose of the spacecraft, according to those on the space station? t= s/v = 57/c = 1.9x10^-7 s (They get 6.3x10^-7 s (consequential 'errors' result) which can be obtained by t= 57 / 0.3c - but this logic seems to contradict einstein's 2nd postulate since the signal must move relative to the spacecraft at c) (c) How far from the space station is the nose of the spacecraft when it receives the radio signal from the reference frame of the space station? S(t) = s(moved) + s(length of ship) s= 0.7c *(1.9x10^-7) + 57 = 97m their answer: 190m (d) What is the time taken for the radio signal to reach the nose, according to those on the spacecraft? t = s / v = 97 / c = 3.2x10^-7s their answer: 2.67x10^-7s What am i doing wrong? Thanks.