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Physics Forces Question - Please check the attached picture.

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supersmartpants | (Level 1) Salutatorian

Posted June 16, 2013 at 9:48 PM via web

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Physics Forces Question - Please check the attached picture.

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ishpiro | Teacher | (Level 2) Associate Educator

Posted June 16, 2013 at 11:30 PM (Answer #1)

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a) All forces acting on mass 2 are:

gravity, force from the student and force from the string 2.

Gravity is `m_2*g` , the force F from the student is given and the force from the string is equal in magnitude to the tension in string 2, `T_2` , according to the third Newton's Law.

Since mass 2 is in equilibrium,

`m_2*g + F = T_2`

Letting g = 10 N/kg,

`T_2 = 40 N + 6*10 N = 100 N`  

Using the same reasoning, the equation for the forces acting on mass 1 is

`m_1*g + T_2 = T_1` , where `T_1` is the tension in the string 1.

Therefore `T_1 = 100 N + 4*10 N = 140 N`

The tension in the string 1 is 140 N and the tension in string 2 is 100 N.

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