Question

I understand that a prokaryotic cell has ribosomes smaller than 70s.

But what i don't understand is what 70s accutually means. Please could someone explain what 70s means to me?

thank you
Ms. Sue
S is a unit of density. Check this site for a clear explanation.

http://student.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/proribo.html