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# Re: [ST] for Marc - (energy)

• Subject: Re: [ST] for Marc - (energy)
• From: "Chris Harwood" <Chris@xxxxxxxxxxxxxxxxxx>
• Date: Sat, 10 Jun 2006 16:33:32 +0100

```Acceleration comes as linear and angular in the UK.  <Puffs out chest in
defiance>

Chris Harwood
00 RS

>>> Emile@xxxxxxxxxx 10/06/2006 03:03:26 >>>
>From: Masiak, Richard
>You forgot rotational acceleration.
>It sounds like you're saying F=ma+(the v of your forward motion)
>I'm not quite sure how many different components of "a" there
>are, but I'm pretty sure I had a rotational acceleration component
>added in there somewhere.
>> From: Bruce Parker
>> a simple high side will generate [your weight times the max height
>> of the center of mass plus the energy of your forward motion].

The V (speed) is not a force, speed is just a relative indicator of
movement per time. When the speed changes (negative or positive
acceleration), that's when the force comes in (F=MA).

Your acrobatic stunt (sounds spectacular, must have been terrifying?)
used the deceleration of the bike (difference in speed between you
and the bike) to create the relative force to bring you over the
handlebar. By holding on to it you vectored that force (acceleration)
eventually downwards, adding it up to the acceleration by gravity.

So in the vertical plane there was one vector of force, caused
by two forces that are added up, which were caused by gravity
and by your relative acceleration which you deflected downwards,
times your mass. You're forward motion is still present, but won't
really become a force untill you start decelerating (by hitting a
wall or by scraping along the asphalt), which would be a force in
the horizontal plane (horizontal vector).

The complete and absolute forward motion only comes into play as a
force into the asphalt if it would have been completely deflected
towards the asphalt. In a highside a large part of the forward
motion (but not all, otherwise it would drop dead still right
after the highside) is indeed deflected suddenly straight into
the asphalt (or whatever platform you're crashing into).

So there's just one sort of acceleration, which can be positive
or negative (deceleration) and can be pointed in any direction
(and can therefor be split up into horizontal / vertical components,
or vectors if you like).

Emile
www.piloot.com
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