Tension in a System: Is My Answer Wrong?

[goldfish9776]

Homework Statement

Isn’t this question same concept as the note as I posted ? I found

P = T + F1+F2= 50(0.3)(9.81) + 50(0.3)(9.81) + (50+100)(0.35)(9.81) = 809.3N

But the ans given is 662.2 N ..

Homework Equations

The Attempt at a Solution

 

[gneill]

Draw the FBD for block B alone. What are the forces acting on block B? Does T act on block B?

 

[goldfish9776]

Draw the FBD for block B alone. What are the forces acting on block B? Does T act on block B?

Draw the FBD for block B alone. What are the forces acting on block B? Does T act on block B?

 

[haruspex]

The question for which the given answer is 662.2N does not have a pulley nor a rope attached to the right of B. Why did you add those to the diagram?

 

[goldfish9776]

The question for which the given answer is 662.2N does not have a pulley nor a rope attached to the right of B. Why did you add those to the diagram?

the question is actually same as the notes that i post , right ?
Actually , i have asked this question earlier...
https://www.physicsforums.com/threa...-tension-of-string.820812/page-2#post-5156741

 

[haruspex]

the question is actually same as the notes that i post , right ?
Actually , i have asked this question earlier...
https://www.physicsforums.com/threa...-tension-of-string.820812/page-2#post-5156741

In the first post of this thread, you attached two problem statements as images.
The first one is a copy the question in the earlier thread. This has the two blocks connected via a string which passes around a pulley (not shown) attached to a wall. Another string pulls on the lower block.
The second image shows the top block tied to a wall. Only one string attaches to the lower block, and there is no pulley. You appear to have drawn in a second string, making it look like the first problem. The two problems are different. If you modify it to look like the first problem then of course you will get the wrong answer.

 

[goldfish9776]

In the first post of this thread, you attached two problem statements as images.
The first one is a copy the question in the earlier thread. This has the two blocks connected via a string which passes around a pulley (not shown) attached to a wall. Another string pulls on the lower block.
The second image shows the top block tied to a wall. Only one string attaches to the lower block, and there is no pulley. You appear to have drawn in a second string, making it look like the first problem. The two problems are different. If you modify it to look like the first problem then of course you will get the wrong answer.

ok , noticed my mistakes