A box of mass 26 kg is hung by a thin string from the ceiling of an elevator. The string can hold up to 276.1 N and will break under larger tension force. How much can the maximum acceleration of the elevator be going upward so that the string does not break and continues to hold the box? I don't even know where to start.

Answer 1

F=ma
276.1=26*(9.81+ a)
solve for acceleration a, going upward.