Physics Help Forum Why is tension added with mg?

 Energy and Work Energy and Work Physics Help Forum

 Apr 29th 2017, 12:39 AM #1 Junior Member   Join Date: Apr 2017 Posts: 2 Why is tension added with mg? Why is my teacher saying that T = mg + ma = 24 N? Shouldn't it simply be 4 N? Link to the question https://ibb.co/dHiDkk
 Apr 29th 2017, 08:26 AM #2 Senior Member     Join Date: Aug 2008 Posts: 113 because ... $F_{net} = ma$ Tension is directed upward, force of gravity is directed downward ... $T - mg = ma$ $T = mg + ma \implies T = m(g+a)$
Mar 29th 2018, 02:54 AM   #3
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Join Date: Mar 2018
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 Originally Posted by skeeter because ... $F_{net} = ma$ Tension is directed upward, force of gravity is directed downward ... $T - mg = ma$ $T = mg + ma \implies T = m(g+a)$
Yes you are right!
What I like about these tasks, the fact that they can be solved with the help of the system of equations and the transfer of terms.

Last edited by topsquark; Mar 29th 2018 at 06:56 AM.

 Mar 29th 2018, 12:19 PM #4 Senior Member   Join Date: Jun 2010 Location: NC Posts: 417 Hi AKM17 Yes, the math works. Set it up and use its operations. (Note: "Net" is not a math operation. A net is for catching butterflies). Don't know your level but here is more reading (of possible interest). About f=mA Blue Ocean Towing Good luck with your studies! JP

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