phy 201
I have understood all the topics that you have went over in class, sometimes I just forget how to do them. I am not confused, just need positive reenforcement.
The question that I have is: I understand now after explination of the Normal force pushing perpindicular to the slope of the surface of incline that is used. I understand that, just in a technical sense, when you pushed the die down onto the rubber band. the contact of the die to the rubber band was greater on the side with the highest elevation than that on the side with the lowest elevation. Therefore it was getting greater push on the side with higher elevation than that on the side of lower elevation. Is that whay the normal force repels perpendicular to the slope even though you were pushing straight down as gravity's force would? Thanks
There were actually two things going on with that rubber band.
One was that the rubber band was deflected from its original straight-line configuration, resulting in a 'slingshot' effect perpendicular to its original direction. When we fully analyze the force vectors that arise in this situation, we'll see precisely why this effect is perpendicular to the original direction.
The other is that due to friction between the die and the rubber band, the part of the rubber band above the die was stretched a bit more than it ordinarily would be while the part below the die ended up stretched a bit less. So the die is pulled upward and to the left more than downward and to the right. The result is that the total frictional force is upward and to the left, essentially along the original direction of the rubber band. This is loosely analogous to a frictional force acting up an incline, though the analogy isn't perfect because the frictional force exerted by an incline isn't strictly elastic in nature.
The point is that both a 'normal' and a frictional force were acting on the die, which would also be the case if the die was on an incline. It's important to distinguish the normal force from the frictional force on an incline. It's very easy to confuse them because they both seem to be coming from the same place, namely the incline, but they arise from very different actions.