Momentum in a mass resting on the Earth's surface

In summary: There must be a reason why it would not be stable. For example, if the bar was not balanced on the Earth's surface, small motions in the air (caused by wind, etc) could cause a net force on the bar that would make it unstable. If all other conditions were perfect, meaning the bar was balanced and the surface was level, the bar would still not topple over due to the Earth's rotation.
  • #1
starz_above
10
0
Hi all,

I'm trying to understand how the forces can modeled in a mass which is resting on the Earth's surface. Please see attached diagram.

It can be assumed that the mass is fixed to the bar and that bar is free to move where it is resting on the Earth's surface.

According to my thinking the mass at the top of the bar has higher momentum due to a higher velocity and mass than that which is at the bottom of the bar, hence this should cause the bar to topple over once any stabilising force is removed.

Am I correct in thinking this?

Thanks for any help.
 

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  • #2
The reason for the bar to topple over isn't momentum due to the rotation of the earth, it is because of instability and gravity.
 
  • #3
Drakkith said:
The reason for the bar to topple over isn't momentum due to the rotation of the earth, it is because of instability and gravity.

What would cause the instability if initially the bar was balanced on the surface of the earth?
 
  • #4
The bar not being flat on the end, small motions in the air resulting in net force on the bar, not putting it on a level surface, and a thousand other little reasons.
 
  • #5
Drakkith said:
The bar not being flat on the end, small motions in the air resulting in net force on the bar, not putting it on a level surface, and a thousand other little reasons.

OK, so if the bar was balanced in a vacuum and the surface was level and all other little reasons were accounted for then would that mean that the bar would not fall over due to the rotation of the Earth?

I was thinking that because there was higher angular momentum in the mass compared to the base of the bar it would cause it to fall over.
 
  • #6
Momentum is not force. Check out Newton's first law and second law.
 
  • #7
A mass sitting on a bar will not necessarily topple over.
 

FAQ: Momentum in a mass resting on the Earth's surface

What is momentum?

Momentum is a measure of an object's motion and is calculated by multiplying its mass by its velocity.

How does momentum change when an object is at rest on the Earth's surface?

When an object is at rest on the Earth's surface, its momentum is zero because it has no velocity. However, the object still has potential energy due to its position in Earth's gravitational field.

Does an object's mass affect its momentum?

Yes, an object's mass is a key factor in determining its momentum. The larger an object's mass, the greater its momentum will be for a given velocity.

How does the Earth's surface impact an object's momentum?

The Earth's surface does not directly impact an object's momentum, but it does affect the object's velocity due to friction. Friction can slow down an object's motion, decreasing its momentum.

Can momentum be conserved on the Earth's surface?

Yes, momentum is conserved on the Earth's surface as long as there is no external force acting on the object. This means that the total momentum of a system before and after an interaction remains the same.

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