Help with Matrix Multiplication

I am very confused by this problem, as it seems very vague for me. Not sure where to even start, the problem is this:

Compute the movement of force around the pivot point for a lever. You'll need to use trigonometry to determine the x and y components of both the position vector and the force vector. Recall that the moment force can be calculated as the cross product: Mo = r * F . A force of 200lbf is applied vertically at a position 20 feet along the lever. The lever is positioned at an angle of 60 degrees from the horizontal.

I understand matrix multiplication but I am not sure what this problem is having me find for the r value in the equation. Also is it asking for different angles around the pivot point and where am I getting the values for the position vector and force vector?

[David Young]

Perhaps it's asking for the moment of the force rather than the "movement"?

To get the values for the position vector and the force vector, it's best to draw a diagram. Then you can just use ordinary trig to get the components.

There doesn't seem to be anything in the question that asks for multiple angles.

Answer 1

[bym]

the r in the equation is the position in x,y,z of the applied force. once you get that you can use

cross(r,f)

to get the moment