My long due Basic Physics Tutorial!

Well, my profile details claim an interest in physics and mechanics...and I don't think I have made even 1 post on that topic. So...here goes.
Be warned...I am not very good at maths...nor drawing. Just try to make pictures in your head. Of course, if you can't, the fault lies with the poor author! :(

Topic 1--> Why is it easier to balance a Bicycle when it moves?

This is something that has forever intrigued me...since I learned how to ride a bike...and had my first fall....which was while stopping the dashed thing!

So here goes. Get your imagination hat...put it on...and read further

Imagine a stationary cycle, with "Yours Truly" seated on it. (I weigh more than 80 kilos). Now, if I tilt sideways even the tiniest bit, the centre of mass of the cycle no longer lies between the wheels...and whoops, the result is an unfortunate bala, smeared with dust/mud. After all, the tiny force that is now not aligned with the centre line of the cycle acts to increase the instability of the cycle, leading to a greater force which is not aligned...which increases it even more...and so on and so forth.

So how is a moving cycle different? After all, when you shift even slightly, surely your weight is not on the centre line of the bike, and the results should be similar. But it does not happen. Why?
Here is why. The rotating wheels have a rotary moment of inertia, which when you tilt them means that there are two more forces sitting around other than just your body weight.

Warning: Tech Data coming up. Skip if you do not want
Any motion in a curved path represents accelerated motion, and requires a force directed toward the center of curvature of the path. This force is called the centripetal force which means "center seeking" force. The force has the magnitude as given below.
Now for the meat...how does this centripetal force come into picture for a bicycle? While the bicycle is perfectly straight...well, it does not. But when you tilt the dashed thing, what happens. Your rotating tyre is also tilting, which now means that the centripetal force, which was doing nothing very special, now suddenly is acting at an angle to the vertical.
This angle means that the centripetal force now has two components....one directed in the vertical direction. ie: towards the sky/ground. And the other, horizontal direction.
Now, vertical makes no difference to us. However the interesting thing about the horizontal component of this force is that it tends to push the weight back to the centre line, thereby keeping the cycle stable.

Now, I dont have a scanner, which lets me write out the equations as well as the figures, so I will save that for another day, but suffice to say, the words above are an (somewhat unclear) explanation of this rather nifty real world problem. I especially like it because this is one thing that I figured out for myself rather than learning from a book. The book gives the information faster, but learning it intuitively is sooo much more fun and enjoyable!

k...any other nifty physical problems...well if you have them, I would be more than glad to think of their solution...but remember, it took me three fruitless years before I actually came up with the above explanation for the cycle thing. So questions are welcome...Just do not expect good answers.

p.s: I have to acknowledge the input of http://hyperphysics.phy-astr.gsu.edu/HBASE/cf.html, for the middle portion of my post, as well as that equation. Their page is not half bad either! :)


Well, till the Zener diode, and how physics is a lot like magic!
Ta Ta.