How Do You Calculate Force Components and Moments in Vector Problems?

[greg997]

Hi,
I ve got two questions.

1. how to find the component of the force F in the direction of the displacement s?

I have two vectors and angle between them.


2. how to find moment of force F when applied at position r= 2a+7b-3c


No idea how to start:(. Thanks for helping me.

 

[LowlyPion]

1) It very much depends on the angle doesn't it? Then which axes you choose to determine he result. I usually choose the axes that make calculation the easiest - like along one of the vectors.

2) Moment is r X F. Your interest then will be in the cross product between the displacement and the force.