HINT:#
The question asks us to determine the radius of the pulsar's orbit around its binary companion.
HINT:#
In Activity 4, we are given the period of X-ray disappearance and we determined the speed of the pulsar in its orbit The prompt for that problem told us how often the signal disappeared. Using our current model for the binary system, we can infer that this is the orbital period.
HINT:#
d = vT
Where:
d = 2πr
v = velocity of the pulsar
T = period of the pulsars orbit
Substituting into our original equation, and solving for r, the radius of the orbit
r = vT/2π
HINT:#
v = 339 km/s
T = 2.1 days
HINT:#
Let's use unit analysis:
r(km) = v(km/s)T(days)/2π
For our answer to be in kilometers, the time unit on the right side of the equation will have to cancel. Let's convert the orbital period into seconds.
T = 2.1 days * (24 hours/day * 60 minutes/hour * 60 seconds/minute) = 181440 s
HINT:#
r = vT/2π
= (339 km/s)(181440 s)/2π
= 9.8 x 106 km

close window