Answers

2014-06-08T21:04:11+08:00
The force of the cupboard is equal to its weight where weight is:

F=W
W=mass x acceleration due to gravity

so the reacting magnitude is equal to it's Force or weight and for the reacting direction
it is the opposite direction of its weight or force. 
The reacting force is what we call Normal force which is equal and opposite direction of the acting force or the weight of the object plus the external forces if there is one.
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