Normal on a mass have different values at pole and equator

In summary, the normal on a mass has different values at pole and equator because the Earth is spinning and the normal is the force that keeps objects in contact with each other when they are moving. The normal at the equator is equal to the gravitational force, but at the pole the normal is equal to the weight of the object.
  • #1
Angie Tom
15
0
why does the normal on a mass have different values at pole and equator
 
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  • #2
This requires an understanding of circular motion and centripetal force. Draw out a free-body diagram as such:

- A circle representing the Earth;
- A rectangular block representing a man (or any mass) standing at the equator;

Recognize that the Earth is spinning about an axis passing through its centre, then think about what are the forces acting on the man?
What is/are the force(s) contributing to the centripetal acceleration of the man such that he can travel in a circular motion around the Earth's equator?
Finally, write out an equation relating the forces with the centripetal force (as the net force). Rearrange the terms of the equation such that you get:
N = ...

Now do the same but replace the man at the equator with another rectangular block at the pole. Again, find an expression N = ...

Compare the two expressions for N and you shall see why the normal contact force is different at the poles and at the equator.
 
  • #3
JeremyG said:
This requires an understanding of circular motion and centripetal force. Draw out a free-body diagram as such:

- A circle representing the Earth;
- A rectangular block representing a man (or any mass) standing at the equator;

Recognize that the Earth is spinning about an axis passing through its centre, then think about what are the forces acting on the man?
What is/are the force(s) contributing to the centripetal acceleration of the man such that he can travel in a circular motion around the Earth's equator?
Finally, write out an equation relating the forces with the centripetal force (as the net force). Rearrange the terms of the equation such that you get:
N = ...

Now do the same but replace the man at the equator with another rectangular block at the pole. Again, find an expression N = ...

Compare the two expressions for N and you shall see why the normal contact force is different at the poles and at the equator.
This is what I got!
No centripetal force on the mass at the pole as normal is equal to the gravitational force since the mass isn't orbiting in a circle! Its actually revolving around itself!
Right?
 
  • #4
Correct. And what about the situation where the man is standing at the equator?

And finally, where is the normal contact force the greatest? The poles or the equator?
 
  • #5
JeremyG said:
Correct. And what about the situation where the man is standing at the equator?

And finally, where is the normal contact force the greatest? The poles or the equator?
At the equator the normal is equal to the difference between the gravitational force and the centripetal force.
At the pole, normal is equal to weight and so normal is greater at the pole?
 
  • #6
Very good. :)
 
  • #7
T
JeremyG said:
Very good. :)
Thanks a million Jeremy!
 

1. What is "normal" on a mass?

"Normal" on a mass refers to the force that a mass exerts on a surface due to gravity. It is also known as the weight of the mass.

2. Why do normal values differ at the pole and equator?

The normal values differ at the pole and equator because of the Earth's rotation. Due to the Earth's spherical shape and rotation, the gravitational force at the poles is stronger than at the equator. This results in a difference in the normal values at these locations.

3. How does the difference in normal values affect objects at the pole and equator?

The difference in normal values affects the weight of objects. Objects at the poles will weigh more than the same objects at the equator due to the stronger gravitational force at the poles.

4. Can the normal values at the pole and equator change?

No, the normal values at the pole and equator do not change. They are constant and are determined by the Earth's mass and rotation.

5. Are there any other factors that affect the difference in normal values at the pole and equator?

The Earth's shape and rotation are the main factors that affect the difference in normal values at the pole and equator. However, other factors such as altitude and topography can also have a small impact on the difference in normal values.

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