Physics geeks unite! A /beer/exercise conundrum
 

Yesterday I was riding my bike up a local dirtroad, and I got thinking about work (not work work- Kjoule work) and beer. The calorie counter on my garmin was all over the place, and I have never really trusted it, but I got to wonderings.... "hey, me smart- I can do this physics style"

uh... not so quick..

So here is what I am trying to figure out.

My ride is short- about 3 miles, but its a mountain with an ascent of 1540 feet against gravity.

Assuming me plus the fully loaded mountain bike weighs approximately 90kg.

How many calories do I burn climbing it, assuming no friction, etc... just a simple number to represent the energy in calories needed to lift my sorry a$$ 1540 ft.

I assume in a pure lifting motion- this would be mass x 9.8 x height ? right? , but when I plug in the numbers, I get, 90 x 469 meters = 42210 J = 10.19 Kcal?!?!?

This can't be right. I need this number to calculate how much calories I burn, compared to the number of calories in a local beer I drink to come up with the equation

"X times up mountain = Y number of beers"

Important stuff.

Thank you for your help.

Ron

You lost your 9.8 g sub c

You are off by a factor of 10 I think. ~100kcal sounds right. Probably double or triple it with losses however.

THats why good system use cardiac monitors

we are missing crucial data.

what type of beer is this..and will there be snacks?

the calories listed on food items are really kilocalories if I remember correctly

oKAY...
More data. The beer in question is this-

https://www.ratebeer.com/beer/pro-re-nata-claudius-crozet/363281/

It's a light beer, which is okay, because I am a lightweight, but I am having a hard time thinking it is only 144 cal (kcal.. whatever). They serve it in 16 oz and 20 oz glasses. I would assume 144 cal for 12 oz.

I get one or two 20 oz glasses.

I also agree with the kcal vs cal thing, and being off by a factor of ten.

When the calorie counters on the bike are hooked throught the HRM, I get between 250-500 cal for the climb depending on which watch/ powermeter/ garmin thingee I use.

I would assume that the pure climb against gravity would be the majority of the work done vs 3 miles of distance (which isn't a lot for a bike).
The climb is also about 35-45 minutes depending on my out of shapeness, so that would be 35-45 minutes at high aerobic range/ eating dust/ yelling at stray bunny rabbits range.

this is how i remember it as well.

using mgh I get 451272 and this should be in Joules

and using some online converter from Joules to Calories I get 107856 calories

think I need to make my morning coffee and get going

Easiest thread ever.

Yes. ;)



*sub'd, so I can learn a little sumpin'*

http://forums.pelicanparts.com/uploa...1559659639.jpg

if you lift 100kg of mass 1 meter, you did 980 joules of work..correct?

so..just to keep the math simple. add 10kg to your load. 1540 feet = 469.4 meters.

980x469.4= 460004.2 Joules.

man..30 years out of college fades the memory.

Wouldn't your metabolism be different if you drank the beer after cycling or another day when you are just relaxing?

What if you drink the beer while cycling? Do those calories count?