Re: Newbie query: why required weight?

[Truman Prevatt <truman.prevatt@netsrq.com>]

To be percise it is not a question of "energy" it is a question of work.  For
a mass moved up against the amount of work is Fd, where F is the force of
gravity =mg m is the mass and g is the acelleration of gravity.  The path a
horse travels is not parallel to the ground - but more a series of arcs as you
stat,e Bob.  On each arc  the horse is required to perform work.  Since the
work is proportiional to the mass, the more mass the more required work on the
same arc.  The total amount of work required is the sum of the work of each
arc.

There are two interesting things that fall out.  First a horse carrying more
weight is requied to do more work.  The second thing is the higher the apex of
the arc is off the ground, the more work required to tranverse the arc.  This
tells you that a horse with a long low gait does less work to go a given
distance than a horse with a more "antimated"anima - high hang time gait.  So
the daisy clipper will need to do less work to cover the same distance.

I would be pretty simple to calcualte the difference the enegy required for
riders of different mass.  Probably as big a factor is the proportion of the
rider's mass to the horses mass.  A 400 kg horse carrying a 150 kg rider will
have to expend proportionally more work than a 500 kg horse carring a 100 kg
rider.

That is the physics - but I will allow others to bebate the merits of
heavyweight vs feather weight.

Truman



Robert Morris wrote:

> Joe & Ride camp:
>
> You state:>>> Sorry, Bob, but your physics is off.  Energy is only expended
> moving a
> > mass against resistance (such as gravity).  It takes more energy to
> > *lift* a given weight a given height, but not to move it horizontally.
> > All else being equal it takes no more energy to move 200 pounds one
> > *level* mile than to move 100 pounds one level mile.>>>
>
> This is absolutely correct but the horse in creating impulsion must lift
> the weight, total weight animal and rider, into the air and then push it
> forward so the factor of gravity, the overcoming of the movement from
> static to dynamic state and the like are repeated over and over. Then you
> have also introduced the factor of elevation change no matter how slight.
> So there is a very distinct "lifting a given weight a given height". That
> weight is the factor that brings forth the necessity for setting some
> standard such as the minimum 165 lb criteria.
>
> <


--
Truman Prevatt
Brooksville, FL

Mystic “The Horse from Hell” Storm
Rocket a.k.a. Mr. Misty
Jordy a.k.a. Bridger (when he is good)
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