How Do You Calculate Tension in a Rope Holding a Box on a Ladder?

[logearav]

Homework Statement

1) A box of mass 42kg sits on the top of a ladder. Neglecting the weight of the ladder, find the tension in the rope. Assume the rope exerts horizontal forces on the ladder at each end.

Homework Equations

m1g – T = m1a

The Attempt at a Solution

T = m1g - m1a
This is the formula i know for calculating the tension
I have mass has 42 kg. But what is the value for acceleration here? Also I don't know because i have values for h and θ in the diagram.

 

[Spinnor]

I think you are missing a critical dimension, see,

Edit, not so sure now, think everything is fine.

 

[Spinnor]

This is more what you want?

 

[logearav]

Thanks a lot Spinnor. So nice of you in explaining the things so beautifully.