Is the Net Force at the Bottom of a Vertical Circle Greater or Lower Than MG?

AI Thread Summary
In the discussion about the net force at the bottom of a vertical circle, it is clarified that the net force is directed upward and is indeed greater than the gravitational force (mg). The confusion arises from the distinction between tension and net force; while tension at the bottom must exceed mg to provide the necessary centripetal force, the net force is the result of the tension minus the gravitational force. At the bottom of the circle, the upward tension adds to the downward gravitational force, leading to a net force that is greater than mg. Understanding this difference is crucial for grasping the dynamics of circular motion. The key takeaway is that as long as tension exceeds mg, there will be a net centripetal force present.
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You are whirling a rubber stopper of mass something attached to a string in a vertical circle at high constant speed. At the bottom of the circle, the net force that causes acceleration is

my answer was Vertically upward and greater in magnitude than MG.
but the answer in the book says
vertically upward and lower in magnitude than mg.

WHY? I don't get this.
At the bottom of the circle, The Centripetal force is the difference of Force tension pointing upwards and force of gravity pointing downwards. So if the netforce is smaller than MG, then there can't be a centripetal force...

please help me out.
 
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If I'm understanding you correctly, you are talking about the tension of bottom vs. top?

The top has less magnitude because the tension [up] is reduced by the Fg [down]. At the bottom, the magnitude is greater because it's tension [down] PLUS Fg [down].
 
You are thinking about the tension while they are asking about net force. As long as the tension is greater than MG, there will be some net centripetal force.
 

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