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    a10p123's Avatar
    a10p123 Posts: 2, Reputation: 1
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    #1

    Mar 3, 2006, 12:51 AM
    Physics
    HI,
    Can anyone explain in detail, Why Bicycle is not falling while riding and whereas in Ideal it falls imm.
    RickJ's Avatar
    RickJ Posts: 7,762, Reputation: 864
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    #2

    Mar 3, 2006, 04:54 AM
    :confused: Huh?

    What do you mean by "not falling while riding and whereas in Ideal it falls imm."
    fredg's Avatar
    fredg Posts: 4,926, Reputation: 674
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    #3

    Mar 3, 2006, 06:40 AM
    Hi,
    Welcome to this site, and thanks for asking a question here.
    Why does a bicycle not fall over when being ridden?
    It's called "center of gravity".
    Every object that has weight, has a center of gravity. It's the point the average weight of the object is centered. It's the "middle" of the weight.
    For example, if you want to balance your computer keyboard on one finger, you would have to hold the keyboard up, on the end of your finger, placed in the middle of the keyboard, at it's center of gravity.
    This center of gravity is the point where the Earth's gravity pull is straight down toward the Earth's core.
    When riding a bicycle, the bicycle's center of gravity is being balanced on the tires, so the Earth's gravity pull is straight down on the tires, and the bicycle is said to be "balanced".
    If you lean the bicycle over, not riding it, then the center of gravity isn't on the tires anymore, not balanced, and will fall when let go.
    Another example:
    If you want to balance a pencil on one finger, you must place your finger under the center of the pencil; called the center of gravity. It will then "balance" the rest of the weight on you finger, and won't fall off. If you place you finger near the end of the pencil, it will fall, depending on which way most of the weight is.
    The Earth's gravity pull "pulls" on the center of gravity of every object that has weight.
    Dr D's Avatar
    Dr D Posts: 698, Reputation: 127
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    #4

    Mar 3, 2006, 07:18 AM
    I believe that what keeps a bicycle upright while moving forward is the "law of conservation of angular momentum" , aka gyroscopic inertia. Do a search for gyroscope, and it will give you as detailed explanation as you wish.
    dmatos's Avatar
    dmatos Posts: 204, Reputation: 26
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    #5

    Mar 3, 2006, 08:40 PM
    In response to Dr D - gyroscopic inertia will not keep a bicycle upright. What actually does keep the bike upright is minute adjustments to the steering that keep the centre of gravity centred over the two wheels. It is developing a feel for these minute adjustments and having them become second nature that people do when learning how to ride a bike.

    Try sometime to ride a bike in a perfectly straight line, like down the centre line of a quiet street. You'll find that you cannot stay upright without steering off the line, even for a little bit. I recall a demonstration once where the steering was locked on a bike. Even at speeds with lots of angular momentum on the wheels, it was impossible to keep the bike upright.
    Dr D's Avatar
    Dr D Posts: 698, Reputation: 127
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    #6

    Mar 4, 2006, 08:48 AM
    I believe that I shall have to eat some crow on this one. In retrospect, gyroscopic inertia would be virtually nill at slow speeds, and maintaining an upright position would be dependent on the balancing skill of the rider. As the speed increases, I still think that the gyro effect makes this task easier, enabling the rider to operate hands free.
    student1985's Avatar
    student1985 Posts: 2, Reputation: 1
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    #7

    Oct 3, 2008, 06:16 AM

    Two vibrating sources emit waves in the same elastic medium. The first has a frequency of 25 Hz, while the frquency of the second source is 75 Hz. Waves from the first source have a wavelength of 6.0 m. They reflect from a barrier back into the original medium, with an angle of reflection of 25 degrees. Waves from the second source refract into a different medium with an angle of incidence of 35 degrees. The speed of the refracted waves is obaserved to the 96 m/s.

    Q. What is the speed of the waves from the first source in the original medium? Which formula should I use...
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #8

    Oct 5, 2008, 08:31 PM

    Hi student1985. Could you please start another thread for your question? Thanks
    student1985's Avatar
    student1985 Posts: 2, Reputation: 1
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    #9

    Oct 6, 2008, 06:58 AM

    What is the speed of the waves from the second source in the original medium? Explain your answer.
    A.E's Avatar
    A.E Posts: 7, Reputation: 1
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    #10

    Jul 15, 2011, 07:52 AM
    I think the bicycle does not fall because the center of gravity due to motion of the bicyle keeps changing and thus the equilibrium is disturbed and set up at every point of the path of motion.
    Just an idea.Criticism and suggestions will be gladly accepted.
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #11

    Jul 15, 2011, 08:01 AM

    Criticism: Check out the date the question was posted before posting an answer. As a matter of fact, this very thread was created in 2006 and 5 years later, I'm use that the asker has already either solved the problem or has growth enough either to know the answer or no longer bothers the answer.
    A.E's Avatar
    A.E Posts: 7, Reputation: 1
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    #12

    Jul 15, 2011, 08:08 AM
    Comment on A.E's post
    Since the equilibrium keeps getting disturbed and setup,the bicycle doesn't get proper state to fall and it remains upright and somehow I think friction against the motion has a great role to keep it upright.But in ideal setup the bicycle topples sideways due to imbalance and inability to maintain equilibrium
    A.E's Avatar
    A.E Posts: 7, Reputation: 1
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    #13

    Jul 15, 2011, 09:01 AM
    Comment on Unknown008's post
    Just expressing my thoughts and also do old questions have to be ignored if u can give a different idea?
    Unknown008's Avatar
    Unknown008 Posts: 8,076, Reputation: 723
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    #14

    Jul 15, 2011, 09:40 AM

    You clearly don't know the forum etiquette. When someone posts in an old thread, that thread is said to be revived. This is something that is not appreciated in most, if not all forums.

    It's good that you want to answer questions and provide suggestions, but why are you answering very old questions while you can answer more recent questions and actually help people? There is not much point in posting an answer which will hopefully help a future member while you can right now help people.

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