Science Homework Help

I’m working on a physics question and need an explanation and answer to help me learn.

A 5kg mass is connected to a 10kg mass below it by a string. They are in free fall under gravity (g). An upward force is applied to the 5kg mass. In what circumstances will the upward force be greater than the tension force(T) in the string? I think it will be “under all circumstances the upward force force (F) will be grater than the Tension force (T)”, but the answer is different.Thanks for any help!