Normal reaction in a rolling object

In summary, the conversation discusses the normal reaction to a rolling object on an incline and clarifies that the normal force is shown to the side of the center of mass for clarity in diagrams. It is also mentioned that the normal and gravitational forces have no effect on the rotation of the object because their line of action is through the center of rotation.
  • #1
vin300
603
4
Why is the normal reaction to a rolling object shown to the side of the CM?
Forces must be equal and opposite
Is there a real problem if you assume it through the C?
 
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  • #2
What exactly are you talking about? The normal force exerted by the surface of an incline on a sphere rolling down it? If so, why do you say that the normal force is shown "to the side of the CM"?
 
  • #3
I thought this should be clear
Thishttp://webphysics.davidson.edu/faculty/dmb/py430/friction/rolling.html"
 
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  • #4
vin300 said:
I thought this should be clear
Thishttp://webphysics.davidson.edu/faculty/dmb/py430/friction/rolling.html"
In the first two diagrams, the normal force arrow is shown to the side just for clarity. (Otherwise it would be right on top of the weight force arrow.) There's no implication that the normal force actually acts off to the side.
 
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  • #5
:smile:
 
  • #6
Maybe this will help. If a solid sphere of radius R and moment of inertia I = (2/5) m R2 is rolling (without slipping) down a slope of angle theta, then the accelerating force (parallel to the slope) on the sphere at its center of mass is mg sin(theta). But there is an uphill force at the point of contact with the slope (not at the sphere's center of mass) that is accelerating the rotation of the sphere. Also, for completeness, the normal (perpendicular) force of the sphere against the slope is mg cos(theta).
 
  • #7
vin300 said:
I thought this should be clear
This http://webphysics.davidson.edu/faculty/dmb/py430/friction/rolling.html"
Just under the diagram is this text:

( The normal and gravitational forces produce no effect because their line of action is through the center of rotation. )

So although the diagram has the normal vector drawn a bit to side, it actually goes through the center of mass.
 
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What is normal reaction in a rolling object?

Normal reaction in a rolling object refers to the force that a surface exerts on an object in contact with it, perpendicular to the surface. In the case of a rolling object, the normal reaction is the force that the surface exerts on the object to keep it from sinking into the surface.

What is the relationship between normal reaction and weight in a rolling object?

The normal reaction and weight of a rolling object are directly proportional to each other. This means that as the weight of the object increases, the normal reaction also increases, and vice versa.

How does normal reaction affect the motion of a rolling object?

Normal reaction plays a crucial role in the motion of a rolling object. It helps to provide the necessary balance and stability for the object to move smoothly without slipping or sliding. It also helps to maintain the object's speed and direction of motion.

What factors can affect the normal reaction in a rolling object?

The normal reaction in a rolling object can be affected by various factors such as the weight and shape of the object, the type and condition of the surface it is rolling on, and the force or torque applied to the object.

How can normal reaction be calculated in a rolling object?

The normal reaction in a rolling object can be calculated using the equation N = mgcosθ, where N is the normal reaction, m is the mass of the object, g is the acceleration due to gravity, and θ is the angle of the surface with the horizontal plane.

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