Today in class we were reviewing free body diagrams and we encountered a problem where an individual placed a block on their hand with their palm facing the ceiling. This is just a simple free body diagram where there is simply a normal force upwards and gravity pulling your hand down. However, I then wondered what forces would be present if you accelerated your hand upwards, and I reasoned that there would be an applied force and normal force present, however, my friend argued that there would only be an applied force only and I'm just wondering if one explanation is more accurate than the other. This is my first time asking a question on this website so if my question is unclear feel free to let me know and I can make it more clear.

  • $\begingroup$ FYI, "normal" is a direction. It's not a special kind of force. "Normal," in three dimensional space is, to a surface, what "perpendicular" is, in two dimensions, to a line. The force between your hand and the block is also known as contact force, and it is due to interactions between electrons in the atoms and molecules of your hand and electrons in the atoms and molecules that constitute the block. $\endgroup$ Commented Mar 19 at 23:30
  • $\begingroup$ Confusion is obvious i think... To the block, Normal is an applied force. Any force perpendicular to one surface due to the other surface, well, you can name it as "normal". $\endgroup$
    – PinkAura
    Commented Mar 20 at 3:42

1 Answer 1


The applied force is the normal force on the object. The only forces acting would be normal force and gravity.

  • $\begingroup$ I see, so ultimately, because the direction of the applied force is normal to that of the plane of the hand, the applied force is the normal force here. Alright, thanks for the clarification! $\endgroup$
    – James
    Commented Mar 20 at 9:10

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