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Is gravity a constant?

  1. Jan 13, 2017 #1
    Based on my thinking if gravity was a constant wouldn't it be equally hard to walk up a hill versus walking on a flat surface or even going down? Too me it seems like the steeper the angle the more gravity and smaller angles would be less gravity.

    So it is pushing you against an angle.
     
  2. jcsd
  3. Jan 13, 2017 #2
    Hi michaelsrk:
    I think you need to understand gravitational potential energy. The following may help.
    Walking up a hill is harder because your body has to do more work than walking on a level surface. The amount of work needed is the increase in your body's potential energy.

    "Gravity is NOT a constant". The gravitational constant is a constant. That is, it doesn't change with respect to time or place. See

    The force of gravity between two objects depends on the distance between the objects and the masses of the two objects. The force between you and the Earth depends on how far from the center of the Earth you are.

    Hope this helps.

    Regards,
    Buzz
     
    Last edited: Jan 13, 2017
  4. Jan 13, 2017 #3

    Drakkith

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    Staff: Mentor

    Well, the strength of gravity can be approximated as being constant here on the surface of the Earth, but it is obviously more difficult to walk uphill vs walking on a flat surface or going downhill. This is because you have to do work against gravity when going uphill that you don't have to do otherwise. And when going downhill you can let gravity do the work for you, so that is usually much easier.
     
  5. Jan 13, 2017 #4
    Yes that does help, that's interesting. So where is the center of the earth?
     
  6. Jan 13, 2017 #5

    Drakkith

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    Staff: Mentor

    About 6300 km underneath you. :biggrin:
     
  7. Jan 13, 2017 #6
    Hi michaelsrk:
    I do not understand what confuses you about "the center of the Earth". The center of the Earth is like the center of a ball. Where is the center of a ball?

    Regards,
    Buzz
     
    Last edited: Jan 13, 2017
  8. Jan 13, 2017 #7
    You are looking at it from being inside the ball where I am looking at it as being on the ball.
    I think for an object spinning in circles which a gravitational force would be 0 at the top of the spin and at the bottom. I think if the object was rolling the objects center would be at the left and right.
     
  9. Jan 13, 2017 #8
    Hi michaelsrk:

    The center is on the inside. It is NOT on the surface.

    Regards,
    Buzz
     
  10. Jan 13, 2017 #9
    so then the center is equal to a flat space and as you get further from the center it becomes more round and gravity would be equal in all directions?
     
  11. Jan 13, 2017 #10
    The center is a POINT, not a flat space. For a sphere, like a ball, It is the same distance from every point of the surface. Since the Earth is only an approximate sphere, it's center is approximately the same distance from every place on the surface.
     
  12. Jan 13, 2017 #11
    If you went to the center and stood on it would all distances not equal 0? so then as you got further away from that center the angle would increase?
     
  13. Jan 13, 2017 #12

    Drakkith

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    Michael, I'm having trouble following you. Can you clearly state your setup and question?
     
  14. Jan 13, 2017 #13
    Certainly. If the center of the earth is at the core and all points at the center =0 doesn't that mean http://[PLAIN]http://images.algebraden.com/geometry/big/construct-90-degree-angle-with-compass-6.jpg [Broken] all equal distances from the zero point =90?

    cfnnZS.png maybe this is a better depiction.

    or

    circles based on the center to d
    k8wOVe.png
     
    Last edited by a moderator: May 8, 2017
  15. Jan 13, 2017 #14
    Hi michaelsrk:
    I suggest that you might be best able to learn about gravity by asking the librarian either at your school, or at a library near where you live, to recommend a suitable introductory book on the topic.

    In the mean time, I will try to help you express your questions a bit better.
    The use of "=" does not communicate. Also "all points" is confusing. The center is just one single point.
    I am guessing that what you mean is that the distance of the center point from the center point is a zero distance. Is that what you have in mind?

    I cannot even guess what you mean by this.

    By the way, would you mind posting the school grade you are in?

    Regards,
    Buzz
     
  16. Jan 13, 2017 #15
    from the center of the first fixed point of the circle to the next center would be 0. traveling on a 90 degree angle gives you each distance from the first 0 point to the second 0 point.

    I have a g.e..d and degrees in pre apprentice electricity and smart meter technician.

    ipG1Jy.png

    This is how you would calculate further 0 points.

    0EbcHc.png here is a semi-3 dimensional image. each new zero point would continue to connect.
     
    Last edited: Jan 13, 2017
  17. Jan 13, 2017 #16
    Hi michaelsrk:
    We are having a vocabulary usage difficulty.
    I don't understand what this means. I don't understand "the first fixed point", and I don't understand "the circle".
    I am guessing that by "the circle" you mean some circle on the surface of the earth. If you mean a circle of some East or West longitude, you can give it some identity by specifying degrees E or W. If you mean some other circle, you need to explain what it is. I can't guess what you mean by a "fixed point".

    Since you are no longer in school, I suggest you go to the city or town library nearest you and ask the librarian for help.

    Also I can't see the images you have put into your posts. How do you generate these images?

    Regards,
    Buzz
     
  18. Jan 13, 2017 #17

    Drakkith

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    Staff: Mentor

    Unfortunately I cannot see any of your links.

    Hold on. The distance between two points is never zero. If it is, you don't have two points, only one.

    If you are at the center of a circle or sphere, then moving outward, directly away from the center (known as the radial direction), does not change your angle.
     
  19. Jan 13, 2017 #18
    Each new point created represents 0. going from the point of the center to the new centers (zero points, which I mean by where zero would connect again too the next 0.)
    http://imageshack.com/a/img923/4547/ipG1Jy.png
    [PLAIN]http://imageshack.com/a/img923/4547/ipG1Jy.png[PLAIN] [Broken]

    Here I took four 90 degree angles and rotated them to form an overlapping pattern of where 0 is in the very center of this graph(it looks like a square with an x through it). this is now a 3d image where spheres turn into circles and circles turn into spheres. Using the distances of "d" to create equal circles from the center of the square that forms in the actual center.[/PLAIN]
     
    Last edited by a moderator: May 8, 2017
  20. Jan 13, 2017 #19
    Hi michaelsrk:
    What does one circle in your image represent, say for example the particular circle nearest to the origin of your graph towards the north-east?

    Regards,
    Buzz
     
  21. Jan 13, 2017 #20
    Yes northeast is equal distances to southwest northwest is equal to south east.
    http://imageshack.com/a/img923/4547/ipG1Jy.png

    can I make it more 3d in 2d?
     
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