Why is the Normal Force Neglected in Certain Scenarios?

In summary, the normal force is a reaction force that occurs when an object is in contact with a surface. It is determined by the weight of the object and the surface it is in contact with. The normal force is always perpendicular to the surface and can never be greater than the weight of an object. It is present on all surfaces that an object is in contact with, even in cases of seemingly floating objects.
  • #1
nomorenomore
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attachment.php?attachmentid=67312&stc=1&d=1394118481.jpg


So why does normal force of the wheel not counted or drawn in the diagram??
Isn't it that whenever there's mg, there's also Fnormal?

Thanks!
 

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  • #2
It looks like it's because the problem involves the wheel going up off the ground to the next step, so if the force is large enough, then the wheel will be up off the ground and so there won't be a normal force.
 
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1. Why is there no normal force on an object at rest?

The normal force is a reaction force that occurs when an object is in contact with a surface. If an object is at rest, it is not experiencing any acceleration or movement, and therefore there is no need for a normal force to counteract any other forces.

2. What determines the magnitude of the normal force?

The magnitude of the normal force is determined by the weight of the object and the surface it is in contact with. The normal force will be equal in magnitude to the weight of the object, as long as the object is not accelerating.

3. Why is the normal force perpendicular to the surface?

The normal force is always perpendicular to the surface because it is a reaction force to the force of gravity pulling the object towards the surface. The surface is the only point of contact between the object and the external world, so the normal force must act directly away from the surface to prevent the object from penetrating the surface.

4. Can the normal force ever be greater than the weight of an object?

No, the normal force can never be greater than the weight of an object. The normal force can only counteract the weight and prevent the object from falling through the surface. If the normal force were to be greater than the weight, the object would experience a net upward force and would accelerate upwards, violating the principle of equilibrium.

5. Is the normal force present on all surfaces?

Yes, the normal force is always present on all surfaces that an object is in contact with. Even when an object is seemingly floating, such as a balloon, there is still a normal force acting on it from the air molecules pushing against the surface of the balloon.

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