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Newton's Third Law Problems

  • Thread starter forcefrom
  • Start date
  • #1
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Alright, so I have this sheet for homework and I'm not sure where to start.

Incase you are unable to see, the questions say:

a) What is the acceleration of the system and the tension in each rope if the girl lifts with a force of 100.0N?
b) What is the force that she pulls with if T3 (bottom bucket) = 15.0N?

http://imageshack.us/photo/my-images/696/photowda.jpg/

To begin, I know I need to utilize the second law's equation F=ma, but I do not know which masses I am supposed to use to find Fg = gm.

I need serious help, I am completely confused!
 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,230
31
To find the acceleration of the system, you can replace the entire system by an equivalent mass M and a tension T.

So M would be the sum of the 3 masses and T would T1+T2+T3 (they told you what 'T' was in the question.)

Just formulate the resultant force and you should get it now.
 

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