Solving Simple Pulley Question: Magnitude of Reaction Force on Pin A

[Dalmighty]

Homework Statement

A mass of 11.4kg is connected to a long pinned horizontal rod via a pulley. The rod has a mass of 3.8kg and a length of 1.5m and is connected to a wall with pin A. At the instant where the rod is horizontal, the mass M has a vertical velocity of 6.6m/s.

Assuming the pulley has negligible mass and all friction forces are minimal, what is the magnitude of the reaction force asserted on pin A?

Homework Equations

W=mg
I[r] = (1/3)*ml^2

The Attempt at a Solution

This question looks really simple, except I'm not sure how the stated velocity of the mass affects the question (if it does).

I started with a simple FBD where
Mg = M[r]*g+R[a]
That didn't work.

I looked at the question, and it was in the kinematics section, so I tried finding the moment of inertia of the rod, which is:

I[r] = (1/3)*ml^2=2.85
and alpha(I[r])+R[a] = Mgl
But without any way to find the angular acceleration... you can't equate it to the moment force caused by the mass.

Does the upwards velocity of the mass cancel out its weight? or is it a distraction from the question? I'm going to guess I overlooked something easy.

Any explanation of how the velocity factors into the question and how to solve this type of question would be appreciated. Thanks.

 

[ehild]

Can you show a picture of the set-up?

ehild

 

[wbandersonjr]

Where is the connection of the rope to the long rod, in the middle, on the end? Also, what is the angle that the rope makes with horizontal at the instant that the rod is horizontal?

This information is needed.