15. We convert meters to astronomical units, and seconds to minutes, using
1000 m
=
1 km
1 AU
=
1.50
× 10
8
km
60 s
=
1 min .
Thus, 3.0
× 10
8
m/s becomes
3.0
× 10
8
m
s
1 km
1000 m
AU
1.50
× 10
8
km
60 s
min
= 0.12 AU/min .