- #1
Like Tony Stark
- 179
- 6
- Homework Statement
- See below
- Relevant Equations
- ##\Sigma F=0##
##\Sigma M=0##
My question is: given a rigid body which interacts with a surface, what's the direction of the normal force? Because, as the word says, it has to be normal to the surface. But when treating problems of a vertical rod which is slightly pushed and forms an angle ##\theta## with the surface, some people draw it as parallel to the rod, not normal to the surface.
Also, in this example, why does friction act on the body? I mean, there's no force that has to be compensated (in the x axis), normal force and weight are the only forces acting on it (in the y direction).
This is not like the case of the leaning ladder, which has a horizontal normal force and so the friction must act for the body to be static. If there was no friction, would the ladder be "pushed" by the wall?
Also, in this example, why does friction act on the body? I mean, there's no force that has to be compensated (in the x axis), normal force and weight are the only forces acting on it (in the y direction).
This is not like the case of the leaning ladder, which has a horizontal normal force and so the friction must act for the body to be static. If there was no friction, would the ladder be "pushed" by the wall?
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