Here's the question you clicked on:
Rezz5
what does it mean by "A particle of unit mass..."
it mean in the equation you are about to use substitute m=1
maybe some more context would help
In physics you need to determine the mass so, you should you the International System.
See more here. http://hyperphysics.phy-astr.gsu.edu/hbase/mass.html
@UnkleRhaukus , I think you are right, When I use m=1 it made sense, I even worked out that m=1 thanks.