Treadmill physics question

Makes sense to me.
What friction are you ignoring though?
Because the treadmill applies its force through friction.

We can't just ignore friction (and I don't see why you'd want to). If the treadmill has better grip you will use less energy. If the ground has better grip the opposite is true. Now I don't think most treadmills have poor grip. It's a core feature.

The only reason I can see running outside would be easier is if you have the wind in your back.

And if we're just considering how exhausted you get often if you run outside you need to adjust the angle of your feet, which is energy you output. There's also the additional inefficiency of climbing steep hills and going down hills.

I'd say treadmills are far easier to run on, at least here in the woods.

>>7850864

Well, yeah. The foot is also applying its force through friction.

What I meant was, I'm ignoring any friction that doesn't contribute to the lateral movement of the foot, since we're only focused on lateral movement.
Such friction would be rather small, anyway.

>>7850866

I meant to only refer to friction that doesn't contribute to lateral movement of the foot/person.
Sorry if that was unclear.

>The only reason I can see running outside would be easier is if you have the wind in your back.
Just because I'm moving my feet the same amount in each exercise, doesn't mean I'm exerting the same amount of force during that period.

>And if we're just considering how exhausted you get often if you run outside you need to adjust the angle of your feet, which is energy you output. There's also the additional inefficiency of climbing steep hills and going down hills.
Well of course any incline in either system would affect it.
I'm talking about a perfect scenario.

Those force diagrams are pretty confused. You're leaving things out.

First of all, they should always be in equal and opposite pairs, acting on different objects.

Second, anything that is not accelerating should have balanced forces acting on it.

Protip: here are your forces
*runner on ground (or treadmill)
*ground on runner
*runner on air
*air on runner

>>7850926

>First of all, they should always be in equal and opposite pairs, acting on different objects.
They're supposed to be.
Maybe my diagram just isn't very clear.
I made it in like 2 minutes.

>Second, anything that is not accelerating should have balanced forces acting on it.
They're supposed to be.
F_you should be equal and opposite to F_trd and T_wnd in the seperate scenarios.

What I'm pointing out is that the two F_you's are different values.

>>7850866
Hmm.
I suppose that makes sense.

Everging you've said can be simplified to "outside, you also have wind resistance."

>>7851005

Well no, that's not what I'm saying at all.
Outside, you only have wind resistance.
On a treadmill, the treadmill is also applying a lateral force to you.

The ground only applies as much force to you, as you do to it.
The treadmill is applying force regardless of whether you do.

>>7851024

Well that's not correct, then. The ground and the treadmill are the same, just in different frames of reference. Standing still on a treadmill and letting it carry you backwards is no different than standing still on the ground.

>>7851064

>Standing still on a treadmill and letting it carry you backwards is no different than standing still on the ground.

If they're the same, then why does the treadmill apply a lateral force to you?

If you stand still on the treadmill, you're actually moving in reference to the treadmill.

Treadmill are easier because they help your leg go back, thus taking function from hamstrings and glutes.

>>7851080

>Treadmill are easier because they help your leg go back, thus taking function from hamstrings and glutes.
You have to provide a forward force equal to rearward force of the treadmill.
Otherwise you'd be accelerating.

Moving your legs at the same speed as a treadmill doesn't require your mass to accelerate in any direction.

Running on the ground requires you to accelerate the mass of your body to that speed.

You aren't actually moving when on a treadmill, the treadmill is whats moving, when you run however it's you that is moving.

>>7851091

>Moving your legs at the same speed as a treadmill doesn't require your mass to accelerate in any direction.

>Running on the ground requires you to accelerate the mass of your body to that speed.

I pointed that out in the first part of my post in the OP.

>>7851090
Yes but when running on ground your glues and hams work to push your body forward

On treadmill they work only to push the leg back.

But I'm just broscience PhD

>>7851128

>Yes but when running on ground your glues and hams work to push your body forward
The only major force they're working against is wind resistance.

>On treadmill they work only to push the leg back.
On a treadmill, they have to oppose the constant force of the treadmill.

>>7851071
>If you stand still on the treadmill, you're actually moving in reference to the treadmill.

No you're not. It just carries you along.

FYI, you also don't need to account for the earth's rotation or its revolution around the sun.

>>7851169

>No you're not. It just carries you along.

Then how do you explain the eventual fall off of the end of the treadmill?

>>7851091
>Running on the ground requires you to accelerate the mass of your body to that speed.

Yeah for like a second. I'd you're ribbing at a constant speed, you are not accelerating. It is no different than running on a treadmill, event there is also wind resistance.

Running on a treadmill with a fan blowing on you would be exactly the same as running outside.

>>7851181

>It is no different than running on a treadmill, event there is also wind resistance.
>Running on a treadmill with a fan blowing on you would be exactly the same as running outside.

An object at rest tends to stay at rest, and an object in motion tends to stay in motion, unless acted on by an outside force right?

In the treadmill situation, what outside force acts on the runner?
The treadmill, right?

In the outside situation, what force acts on the runner?
Nothing besides wind resistance, right?

How are they then exactly the same?

>>7851176
>Then how do you explain the eventual fall off of the end of the treadmill?

It's not infinitely long.

>>7851207

That's nonsense.
If you start at the front of a treadmill, and stand still, you'll move towards the back of it.
You are moving in reference to the treadmill.

>>7851204
>Nothing besides wind resistance, right?

You don't run by pushing off the air, anon.

>>7851228

>You don't run by pushing off the air, anon.
Pushing against the ground is not arresting my motion.

In fact, air resistance is the reason why you have to push against the ground.

>>7851222
you are moving in the reference of the threadmill but it's irrelevant because the contact surface is the thread, not the underlying threadmill.

you are standing still in relation to the thread, the thread is your ground surface.
If the thread were infinitely long you'd still be still in relation to the thread.

At no point you make contact with the threadmill and if you do then it means you are standing still in relation to the threadmill

>>7851246
>In fact, air resistance is the reason why you have to push against the ground.

No it isn't. If you had the wind at your back moving at the same speed as you were running, there would be no wind resistance. That would in fact be exactly the same as running on a treadmill. And if you stopped moving your legs, you would come to a stop, "pulled along" by the surface of the earth.

>>7851248

>you are moving in the reference of the threadmill but it's irrelevant because the contact surface is the thread, not the underlying threadmill.

It's relevant so long as it is applying a force to the person on it.
If you're standing still on the treadmill, then it's essentially the same as the ground, because your velocity is the same.

If you have a different velocity, then it is going to apply a force to you.

If someone is on a moving train, they can run at say 6mph down the train, in reference to the train, just as easily as if they were on the ground.
All you have to do is accelerate up to speed, and maintain enough force to neutralize air resistance.

However, if the train is moving forward at 6 mph, and you want to be at 0 mph relative to the ground,
you have to neutralize the force of the train that is trying to accelerate you to 6mph.

>>7851266

>No it isn't. If you had the wind at your back moving at the same speed as you were running, there would be no wind resistance.
If there is no wind resistance, then nothing is decelerating you.
And it then takes no force to maintain your speed.

>That would in fact be exactly the same as running on a treadmill.
Running on a treadmill requires a force equal to and opposite that imposed by the treadmill.

>And if you stopped moving your legs, you would come to a stop, "pulled along" by the surface of the earth.
You're going to have to rephrase this.

>>7851276

So you're actually claiming that running inside a train is more difficult depending on whether it is moving? Because I can assure you it isn't.

>>7851276
no.
stop confusing the thread with the threadmill.

the threadmill has a thread on it that rotates, you are in contact with that thread, not with the threadmill.

In a train the whole thing is moving, on a threadmill it's just the revolving thread you are standing on.

>>7851286
>If there is no wind resistance, then nothing is decelerating you.
>And it then takes no force to maintain your speed.

Ok, wait for a windy day and try this out yourself. Start running in the direction if the wind, then stop moving your legs. See if you keep moving forever.

>>7851293

No, I'm saying that keeping a pace equal but opposite to the train you are running inside of, to keep your speed relative to the ground at 0 is more difficult.
Because the train is applying a force to you.

>>7851327
>No, I'm saying that keeping a pace equal but opposite to the train you are running inside of, to keep your speed relative to the ground at 0 is more difficult.

Well, you're wrong about that. Running forward at 6mph is exactly the same as running backwards at 6 mph. It's also exactly the same whether the train is stopped or moving at 6 mph or moving at 200 mph.

>>7851327
This is my post, and I made a mistake.
I was still thinking about treadmills.

What I should say is that it's just as easy to run inside the train, because unlike the treadmill, you are moving relative to the train.

>>7851351

Yes, I amended my post here.

>>7851360

A treadmill is different because running on the treadmill doesn't move you relative to it.

Running on a treadmill is easier than running outside, this is common knowledge and I've never heard anyone claim otherwise.

>>7851382

Well then let me be the first.

>>7851387
And let my show you that you're wrong.

http://www.ncbi.nlm.nih.gov/pubmed/8887211

>>7851360
>because unlike the treadmill, you are moving relative to the train.

You are moving relative to the treadmill. That's the whole point of it.

>>7851448

That shows that you are wrong, actually. The difference is because of wind resistance, I.e.>>7851005

>>7851484
This will not. Small prop-planes might I think

>>7851473

The treadmill is going to apply a force to you if you are not moving at the same speed as it.
The train isn't.

For example, if I take a ball and roll it slowly down a train, (discounting air resistance), it's just going to keep rolling.
If I do the same on the treadmill, it'll roll back and fall off the end.

>>7851448

This makes no mention of the forces involved, and doesn't address any of the points I made.

>>7851494

Most trains are not infinitely long, actually.

>>7851483
> The difference is because of wind resistance

I never claimed it wasn't, only that running on a treadmill was easier than outside...

Or are you claiming that wind resistance makes running outside easier? Because the experiment I posted and simple common sense would suggest otherwise.

>>7851500
If you're the person who replied to my post the only point you made was that I'm wrong to claim running on a treadmill is easier. If not then I wasn't replying to your points in the first place.

>>7851502

Yes, unlike a treadmill.
Your point?

>>7851510
>I never claimed it wasn't

You most definitely did:

>>7851024
>Well no, that's not what I'm saying at all.

>>7851517

My point is like I said in the OP.

A treadmill creates a force in the direction opposite to the way you're running.
If you don't oppose this force, you'll be accelerated in the direction of the treadmill and go off the end.

When you're running on the ground, the only force opposing you is the wind.

>>7851537

Did you know that the Earth rotates? Confirm if you do.

>>7851064
this is a semantic problem, unlike the Earth a treadmill has two parts: moving and non moving.

Standing on the moving belt means you're moving back from the front of the frame, but your position on the belt hasn't changed, which is what really matters.

>>7851554

What does that have to do with anything?

>>7851574

Is that a yes?

>>7851598

Relative to itself, the Earth is stationary.
Relative to itself, a treadmill is moving.

So you may wonder why you can't look at the belt of a treadmill as its own entity.

Its because you aren't trying to move yourself relative to the belt.

If you could somehow stay on the belt for its entire rotation, (pretending gravity didn't pull you off, and there was space under the treadmill to fit)
you would have the same amount of total force that pushed you backward as forward.
It would push and pull you the same total amount for one revolution.
Only in that case, could you move with the same amount of effort as running on the ground.

Going back to the OP, the F_trd backward would be equaled out during a full revolution with an F_trd forward

>>7851667
>Relative to itself, a treadmill is moving.
It stays in the same spot, heffe

>>7851574
>What does that have to do with anything?

Because the earth's surface is "dragging you along with it" at hundreds of mph. But that doesn't really matter to your run, does it? All that matters is your speed RELATIVE to the surface you are running on, whether it is the earth, a train, or the belt of a treadmill.

>>7851677

By that logic, the person running on the treadmill isn't moving.

>>7851667
>Its because you aren't trying to move yourself relative to the belt.

That's exactly what you're doing.

>>7851682

>Because the earth's surface is "dragging you along with it" at hundreds of mph.
That implies it's applying a constant force to you.

>But that doesn't really matter to your run, does it? All that matters is your speed RELATIVE to the surface you are running on, whether it is the earth, a train, or the belt of a treadmill.
The belt of the treadmill moving back at a constant speed, requires you to move forward to stay in position.
That's because you can't follow it through its entire cycle.
The same isn't true of the earth or a train.

>>7851691

Yeah, I meant to say "you aren't trying to stay in position relative to the belt"
I misspoke.

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15KB, 315x147px

>>7851536
I most defiantly didn't.

Pic related.

>>7851537
Whenever you're touching the ground, as most people do fairly regularly when running, then there's friction between you and the ground. If you can't get your head around that then there's no helping you.

>>7851696

The Earth moves at a constant speed. So do trains, most of the time. Try again.

>>7851717

>Whenever you're touching the ground, as most people do fairly regularly when running, then there's friction between you and the ground. If you can't get your head around that then there's no helping you.

That friction force would be exactly the same on a treadmill though.
The treadmill is adding an opposing force trying to accelerate you backwards.
Running on the ground is adding an opposing force of air resistance.

>>7850866
agreed, OP is retarded and does not know basic physics

nice bait op

>>7851736

Show what's wrong with the force diagram.

>>7850838
>Many people on the internet claim that running on a treadmill requires the same amount of exertion as running on solid ground.

That's the dumbest shit I've heard today. If you don't at least crank up the incline on a treadmill to 2.5% or so, adding the force of gravity to compensate, you can very easily tell that it's tougher (and more rewarding) to run outside than to run on the human hamster wheel.

I haven't done either in far too long, but maybe I'll fix that today thanks to OPs science.

>>7851753

In my experience, it's much harder to run on a treadmill.
I feel like I have to push a lot more.
When I run outside, my momentum carries me forward.

>>7851753

Thanks for the bro science input, but we've been over this already. The only difference in running outside is the wind resistance. Running with the wind at your back is the same as a treadmill. Running on a treadmill with a big fan in your face is the same as running outside.

>>7851771

When you're running outside, nothing but air resistance is pushing you in the opposite direction.
On a treadmill, the treadmill is pushing you in the opposite direction.

It's totally different.

>>7851729

Yes, friction between you and the moving belt is trying to accelerate you backwards., you have to fight this force to remain stationary.

While running on the ground friction is trying to bring you to standstill. You have to fight this force to remain in motion.

They would be exactly the same if it wasn't for air resistance. You're absolutely right.

>>7851814

>While running on the ground friction is trying to bring you to standstill. You have to fight this force to remain in motion.

The same force exists on the treadmill.

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i think i understand it, boys

>>7851897
should be a reply to >>7850838