Your groceries are in a bag with paper handles. The handles will tear off if a force greater than 50.8 N is applied to them. What is the greatest mass of groceries that can be lifted safely with this bag, given that the bag is raised with constant speed.
Normal force is acting up on the bag, and that is given to be a maximum of 50.8 N. To balance this force is the mg force which points strait down towards the ground. By equating mg = 50.8 and g = 9.81 then you can solve for m.