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Comment by gerdesj | Hacker News Reader

Assume a spherical horse ...

OK are we talking a Mustang or a Shire or Clydesdale? Carrying the food or dragging a wagon?

I don't know enough about horses but a heavy horse (Shirehorse, Suffolk Punch or Clydesdale in the UK) can drag quite a decent load. Granddad's Clydesdale "Damson" could make a furrow with a plough all day, back in the day - bloody hard work. Ironically, that was in Devon - Scottish horse in Shire land! He got a Ferguson tractor later but they kept the horses as well.

I think we would run out of UK for a single horse load unless doing the full Land's End to John o'Groats (or trying to cross the Irish Sea) but a bigger land might need a re-fuel or two.

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> I don't know enough about horses but a heavy horse (Shirehorse, Suffolk Punch or Clydesdale in the UK) can drag quite a decent load.

A heavy horse also needs to eat a lot more than a normal horse.

... but it can also drag a lot more too.

Now, can our nag drag enough fodder to do the job? I suggest yes.

Yes, a heavy horse can drag more.

But the question here is how far the horse can go on a single load of food. We're purely trying to convert food into work via the horse.

And if you assume that the conversion of potential energy stored in the food to actual energy produced by the horse is less than perfectly efficient, then it will always be better to avoid doing work than to try to make up for doing extra work by starting with more food. That would be true even if starting with more food didn't require doing even more extra work to move the extra food.

Improvements in strength aren't helpful to this problem; what you need is higher efficiency.

re: dragging a decent load

My father, born in 1930 in Minnesota, told of watching farmers bringing out a team of horses to help pull stuck tractors out of the springtime mud -- it wasn't only about their not-insignificant strength, but their superior traction. In his teens -- which would have been in the forties, he worked with teams of horses, which seems oddly late in the 20th century, but he did, as did my paternal grandfather. The terms for the various parts of the, to me, very-complicated-looking harnesses were as fresh in his mind in his eighties as they had been in his teens.

A healthy horse just walking (not doing heavy work) can keep going on fat reserves for several days. Just like most other large mammals.

If the horse is spherical, I'm sure he's got plenty more fat reserves than that!

> If the horse is spherical, I'm sure he's got plenty more fat reserves than that!

If we assume a spherical horse, we can also assume lack of friction.

Then for about 50% of the mountainous part, the horse can just roll downhill not even using any of its precious fat!

and for flat areas, it just needs the energy for initial acceleration, then it can continue in a uniform rectilinear motion

Can we have upright cylindrical goats on the flat parts for our horse to knock down like skittles? Please?

I don't see why not. Crack on!

Yes but with negligible mass to avoid slowing down the spherical horses

With a bit of tuning the oat moped can perhaps recuperate some energy upon breaking too.

+1 insightful!

I am reminded of this: https://youtu.be/ba62uuv-5Dc

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