Find Max Weight of Block A to Keep Block B Stationary

[bob1182006]

[Solved] Tension Help

         T2 /
---_T1____./ 41*
  B       |
---       |
         |  |
         |A |

A and B are blocks. B is stationary on a tabletop. A is hanging off the edge beind held by 2 strings.

Homework Statement

Block B weighs 712N. The coefficient of static friction between block B and the table is 0.25. Find the maximum weight of block A for which block B will remain at rest.

Homework Equations

F=ma

The Attempt at a Solution

Block B:
$$f_{smax}-T_1=0$$
$$f_{smax}=T_1$$
$$f_{smax}=\mu_{smax}m_Bg$$

Block A
$$T_1-T_2\cos41=0$$
$$T_1=T_2\cos41$$

I can't figure out what T2 is. I thought at first it would be $$m_Ag$$ But plugging that in I get mass of Block A is 235.85N but it should be 155N.

Edit: forgot about the tension between block A and the string holding it up which allowed me to get 154.7~155N when rounded.

 

[learningphysics]

Look at the knot joining the two ropes..

write the $$\Sigma{F_y} = 0$$ equation...