FB Diagram Problem: Is My Sketch Correct?

  • Thread starter chemic_23
  • Start date
  • Tags Tags
    Diagram
5 replies · 3K views · last reply
chemic_23
Messages
44
Reaction score
0

Homework Statement



Three diagrams: a free-body diagram for the bucket showing tension T upward and weight W downward; a free-body diagram for the pulley showing tension T pointing left and tension F pointing right; and an illustration of a pulley with rope over it, F horizontal to the right, T down to a bucket labelled W.


Homework Equations



Is my sketch(illustration) and fbd correct? Is T(orange) = T (blue)?

The Attempt at a Solution

 
chemic_23 said:

Homework Statement



Three diagrams: free-body diagram of the bucket with upward tension T and downward weight W; free-body diagram of the pulley with tension T pulling left and force F pulling right; and an illustration of a pulley hung from above with rope tension T down to a bucket labeled W, and force F pulled horizontally to the right.


Homework Equations



Is my sketch(illustration) and fbd correct?
Yes, for the bucket. The fbd of the pulley is not correct, your forces are not in the right direction, and there is an additional force on the pulley not shown at the point where it is supported. But don't worry about the fbd of the pulley, since you don't need that one.
Is T(orange) = T (blue)?
Yes, as long as the pulley is frictionless and massless.
 
can you give me the correct fbd for the pulley? I just want to know.
 
I think fbd: (pulley) should be fbd: (hand)? is it correct?
 
As Jay mentioned, you don't need the force diagram for the pulley since all it does in this question is change the direction of a force. In this case, a force F causes a tension T in the rope, which is redirected to pull the block upwards.

Perhaps what you need is a force body diagram for the hand/thing that provides the force F.
 
chemic_23 said:
can you give me the correct fbd for the pulley? I just want to know.
jaseh86 is correct. If you want to know the free body diagram of the pulley,which must be anchored to a table or such, you have T acting to the right, and T acting down (the rope tension), and for equilibrium, you must have the table supporting reaction force, R, acting up and to the left at a 45 degree angle thru the center of the pulley (R= T/cos45 = 1.414T). But don't fool with it.