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Drinking When Riding. The Bike Gets Lighter, But Does The Overall Mass Go Up, Or Stay The Same?....

by Richard_pics
Wed, Mar 25, 2020 10:57
12

Basically im at work, but bored and in a thoughtful mood, so i thought i pose the question below, as i cant seem to find anything clear on google.

Drinking When Riding. The Bike Gets Lighter, But Does The Overall Mass Go Up, Or Stay The Same?....

When you drink, your bottle and bike get lighter. But as you take the water on board, does the mass overall stay the same, or does it get lighter?!

Answers below!....

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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12 comments

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mdavidford | 4 years ago
0 likes

The mass obviously increases. Because cake stops.

[Though not in the current circumstances.]

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Welsh boy | 4 years ago
0 likes

Of course, you could always weigh yourself and your bike just before you set off and then again as soon as you finish your ride to find out.  On a warm day and a ride of a couple of hours, assuming you are wearing decent cycling kit which doesnt hold too much sweat,  I guess you would probably lose about 1kg.

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Sriracha | 4 years ago
0 likes

To answer the actual question posed, the mass is unchanged.

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DoctorFish | 4 years ago
1 like

The whole system (you, bike, water) gets lighter throughout the ride as you sweat, pee, breath out moisture.

By drinking you are just moving weight from your water bottle in to you.

 

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Secret_squirrel replied to DoctorFish | 4 years ago
0 likes

DoctorFish wrote:

The whole system (you, bike, water) gets lighter throughout the ride as you sweat, pee, breath out moisture.

By drinking you are just moving weight mass from your water bottle in to you.

FTFY - otherwise 100% correct and model answer.

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John Smith replied to Secret_squirrel | 4 years ago
0 likes

True. Your weight could go up or down depending on a number of things, for a start the gravitational changes as you move and as time passes 

https://www.technologyreview.com/s/614741/can-earths-gravity-really-be-a...

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Canyon48 replied to John Smith | 4 years ago
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John Smith wrote:

True. Your weight could go up or down depending on a number of things, for a start the gravitational changes as you move and as time passes 

https://www.technologyreview.com/s/614741/can-earths-gravity-really-be-a...

And (according to Einstein) how fast you're going...!

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hawkinspeter replied to Canyon48 | 4 years ago
1 like

Canyon48 wrote:

John Smith wrote:

True. Your weight could go up or down depending on a number of things, for a start the gravitational changes as you move and as time passes 

https://www.technologyreview.com/s/614741/can-earths-gravity-really-be-a...

And (according to Einstein) how fast you're going...!

If you're going to get all relativistic, then you'd have more mass at the top of a hill (due to potential energy) than the bottom. However, you may have less weight as the hill-top will probably have slightly lower gravity.

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Dangerous Dan | 4 years ago
0 likes

Try a search for "respiration".

If you are breathing in oxygen (O2) and breathing out carbon dioxide (CO2) you are losing mass.  You are probably also losing water through sweating and the moisture in your breath.

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Richard_pics replied to Dangerous Dan | 4 years ago
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But are you loosing more mass in sweat than you are taking on board? or less?

 

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Welsh boy replied to Richard_pics | 4 years ago
0 likes

By drinking, all you are doing is redistributing the mass (ie from the bottle into you) so any water leaving your body (sweat, snot, spit, respiration) is going to lower the overall mass.

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Dangerous Dan replied to Richard_pics | 4 years ago
0 likes

That all depends on how much you perspire.  The total mass will decrease, but as others have pointed out, not by very much.

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