Physics
posted by Sammy .
The maximum force a grocery sack can withstand and not rip is 250 N. Calculate the greatest acceleration 20 kg of groceries can be lifted from the floor to the table such that the sack does not break.

Well you know the force and mass.
So use this formula: F=ma.
F=250N
m=20kg
Just rearrange it and you will be able to get the maximum acceleration the sack can withstand before breaking. 
lifted at constant velocity?
F=mg
lifted at a constant acceleration?
F=m(a+g) solve for a