Crane (the mechanism) is made of a massless arrow AB , which is connected to a wall with a hinge and a massless rope CB. There is a weight P=2000N attached to point B. Find the tension T in rope and the force Q acting on the arrow AB. BAC=15 degrees, ACB=135 degrees. (will add a picture in a minute)

Question

anonymous · Answer

attachment

anonymous · Answer

I'm guessing it's looking for the forces acting along BC and BA.
There are three forces in equilibrium, so you can break everything into horizontal and vertical components and set the sum of all components equal to zero.

anonymous · Answer

Isnt there a normal reaction with an unknown direction at point B though?

anonymous · Answer

No, all the reactions and directions are known (or can be found).

anonymous · Answer

There has to be a force upwards (if we have forces P, Q and T, then the y-projections of all of them are in one direction, therefore there can not be an equilibrium, if we dont have a normal reaction somewhere.

anonymous · Answer

AC is in equilibrium, so there is a net vertical force up along AC = 2000 N.

fellowroot · Answer

Are we finding the tension in the rope from CB or from BP? Are these tensions different?

anonymous · Answer

We are finding the tension in the rope CB. I am sure that these tensions are different.

anonymous · Answer

I think you can solve this simply with sum of torques.  
with the axis at A:

Tcos60 = 2000cos75