Wind affect on going uphill and downhill question

[Accy cyclist]

I'll give you an example then maybe someone can tell me why/how it happens. Yesterday it was extremely windy. I went for a ride on one of my usual routes which as in most cases around here involves climbing and descending hills. I've noticed over the years that i usually climb this particular hill at 9mph and descend it at 21mph. That's if there isn't any wind. Yesterday's strong wind made me climb this hill at 11mph and descend it at only 14 mph. I think there must be an obvious answer that someone's going to point out to me,but i just can't fathom it myself. Why does wind assistance put only 2mph on my usual speed,but wind resistance takes 7mph off my usual speed?

 

[gavroche]

Maybe the reason is gravity. Even with the wind behind, you are still fighting gravity as you go up?

 

[bpsmith]

So a 22% gain in climbing and a 33% loss in descending.

 

[Accy cyclist]

Maybe the reason is gravity. Even with the wind behind, you are still fighting gravity as you go up?

I don't know. I'm waiting for a CC scientist to come on and explain it to me. I think it'll take someone with at least a degree in Physics,or something like that. Mind you,the other week i said that going downhill on a carbon fibre bike was harder than on a steel one, as with it being lighter it won't descend/fall as fast. Someone down my local pub after i'd made the comment told me that all objects descend/fall at the same speed no matter their weight or shape. I still can't get my head round or accept that one.

 

[Salty seadog]

Someone down my local pub after i'd made the comment told me that all objects descend/fall at the same speed no matter their weight or shape. I still can't get my head round or accept that one

That person was wrong.

 

[gavroche]

It is a shame that both Albert Einstein and Stephen Hawking are no longer with us. They could have explained it at length and you probably still would be none the wiser.

 

[Dirk]

Someone down my local pub after i'd made the comment told me that all objects descend/fall at the same speed no matter their weight or shape. I still can't get my head round or accept that one.

They missed out the part about it having to be in a vacuum.

 

[Welsh wheels]

That person was wrong.

Clearly that bloke doesn't have a science degree...

 

[Welsh wheels]

I don't know. I'm waiting for a CC scientist to come on and explain it to me. I think it'll take someone with at least a degree in Physics,or something like that. Mind you,the other week i said that going downhill on a carbon fibre bike was harder than on a steel one, as with it being lighter it won't descend/fall as fast. Someone down my local pub after i'd made the comment told me that all objects descend/fall at the same speed no matter their weight or shape. I still can't get my head round or accept that one.

Try dropping a hammer and a feather and see which hits the ground first.....

 

[Accy cyclist]

That person was wrong.

That's what i thought,but he's an argumentative type so i just nodded and let him think he was right.

 

[Accy cyclist]

Try dropping a hammer and a feather and see which hits the ground first.....

According to this bloke down the pub,if you throw a tennis ball and a brick off the top of Blackpool Tower at the same time,both will hit the ground at the same time.

 

[gbb]

Clearly that bloke doesn't have a science degree...

You dont have to have one, just be a member of CC....we know EVERYTHING

 

[SpokeyDokey]

Try dropping a hammer and a feather and see which hits the ground first.....

You do realise that you could well be liable, if Accy drops a hammer on his toes, with that advice?

 

[Accy cyclist]

You do realise that you could well be liable, if Accy drops a hammer on his toes, with that advice?

Don't worry,i'll be wearing steel toe cap boots when i try it out later!

 

[winjim]

According to this bloke down the pub,if you throw a tennis ball and a brick off the top of Blackpool Tower at the same time,both will hit the ground at the same time.

The effect of gravity is proportional to mass, so an object with mass 2m will experience gravitational force twice that of an object with mass m.


But... acceleration is also proportional to mass so because that object has twice the mass it also takes twice the force to accelerate it the same amount, so the mass cancels itself out and both objects accelerate the same.