This conversion is tricky...6.3km/sec= ? m/min I haven't ever done a double conversion like this. Not sure how to proceed. Thank you.
Double unit conversion are no different from single conversions; in fact, double conversions are two single conversions in a row.
In your example, you have to go from km per second to meters per minute. Here's how you'd go about doing that
Notice how I used one conversion factor to go from km per second to meters per second, then another conversion factor to go from meters per second to meters per minute.
So, every time you have to do multiple unit conversions, use intermediaries to get you closer to the desired units.
This is just like multiplyng a series of fractions to get to a desired number