The force used to carry the box up the stairs is 500 N.
Force is an agent which causes a change in the motion or position or state of an object.
Force on the boy = 40 * 10 = 400 N
Force on the load = 10 * 10 = 100 N
Total force = 400 + 100 + 500 N
Therefore, the total or net force used to carry the box up the stairs is 500 N.
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