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Physics fun - rolling downhill
Did you know.... you would need a ramp five miles high to be able to freewheel from Los Angeles to New York? Me neither....
I've also learned you can do an Everesting with "just" three uphill efforts - you can ride from sea level to 10,000ft on Maui Island, Hawaii. Oxygen tank optional.
https://www.google.com/search?q=haleakala+downhill+bike+ride
https://www.strava.com/segments/638944
(hey, it's Friday)
If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.
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13 comments
Think the fastest climbing time should be around 5 to 6pm IIRC
The calculations assume the earth is flat. Assuming the earth is a sphere with a radius of 4,000 miles then you also need to get over the 212 mile high hump between New York and LA...
what?
like the ocean tides need to get over the 'hump' between japan and usa? from the point of view of gravity and what is downhill or uphill the radius of the earth makes no difference.
unless the earth were sitting on top of a much larger body whiose gravity drawfed that of the earth.
wonder if the additional gravity fromt he sun is why I seem to climb slower at night, that during the day. and is the best time for climbing when there is a solar eclipse overhead?
This has been measured very carefully and it depends on the phase of the moon, for one thing.
The upshot is equivalent to approx. 0.00173 grammes for an 85kg rider+bike. More than enough for some weight weenies I suspect, especially given it's an infinite Hairsine ratio.
As most of the ramp would be in 'Outer' Space you would indeed need a space suit, but there would also be next to no air resistance, only rolling resistance, you could get quite a speed up if you had a steeper ramp at the start a gentle slope, enough to keep you rolling. Just stuff a newspaper in your suit for re-entry.
Thanks guys. BRB, building something.
Actually, if you measure from the centre of the earth, Chimborazo in Equador is the highest.
http://www.neatorama.com/2011/11/01/the-farthest-point-from-earths-center/
Its why Lands end to John O Groats is the way to go - JoG is closer to the centre of the earth and therefore its downhill. Absolutely nothing to do with the general prevailing winds.
Some Geological trivia. If you measure Mauna Kea from it's bottom to it's top it is actually over 10,000m tall, Everest from bottom to top is a mere 4000m mount McKinley is in fact the tallest mountain in the world at over 6000m.
If it's 25,000 miles(ish) around the equator, it would depend on what gradient you would need to constantly roll along.
A 1 mile high ramp would give a gradient of 1 in 25,000. A 10 mile high ramp would give a gradient of 1 in 2,500. 100 miles high would give a gradient of 1 in 250 so if you assume you'd need a gradient of, say, 1 in 16 to roll, the ramp would have to be about 1,560 miles high.
Take a space suit with you
.
How high would the ramp have to be to make it all the way around the world?
Is that even possible, theoretically?
According to the physics XKCD has worked out, you need 1 mile of height for every 500 miles of horizontal distance. For a 25,000 mile circumference at the equator, that's 50 miles high. That's enough for NASA to grant you "Astronaut" status.
Various sources give a maximum mountain height on Earth of 6-7 miles before gravity makes it collapse under its own weight, so probably not.
More practically, it would probably be a breach of some planning regs - putting someone's garden in the shade, maybe. That sort of thing.
Good stuff: it's the weekend!
Happy Friday!