Things you always wanted to know the answer to [Vol. 3]

[singlecoil]

People who are still doubting should look at this video. The fact that the person's upper body is not moving much is clearly visible. With practice that movement could be reduced further. If she was to walk up a static escalator then she would need to lift her upper body as well and that would cost substantially more energy. This is not exercise statistics, this is basic physics as has been pointed out earlier.

https://www.youtube.com/watch?v=FL1zdvl5VOk

[singlecoil]

SpeckledJim said:

1) The person staying still is putting energy into the downward motion of the escalator. He is helping it descend.

2) That energy matches the gain in potential energy of the ascending man.

1) He is applying a force equal to his own weight, he's not 'putting energy' into the escalator.

2) No, it doesn't.

[Einion Yrth]

Like I said, it's principle of equivalence stuff; either Einstein was wrong, or singlecoil is. I know where I'd be putting my money.

[singlecoil]

Unlike you, Einstein wouldn't have any problem with this question. He would refer you to Newton, who would tell you to read his book and then apply the principles correctly.

[RobinOakapple]

Einion Yrth said:

Like I said, it's principle of equivalence stuff; either Einstein was wrong, or singlecoil is. I know where I'd be putting my money.

It's all very well saying SC is wrong (he isn't) but you need to demonstrate why and you haven't.

[Einion Yrth]

RobinOakapple said:

Einion Yrth said:

Like I said, it's principle of equivalence stuff; either Einstein was wrong, or singlecoil is. I know where I'd be putting my money.

It's all very well saying SC is wrong (he isn't) but you need to demonstrate why and you haven't.

Either he's wrong, or he's right. My ability, or lack of it, to illustrate the physics involved says something about my ability as a teacher, and nothing about the physics. I don't "have to" demonstrate anything, the physics is what it is. Oh, and he is wrong. Tara.

[Hugo a Gogo]

if you're on a train moving at a constant speed, is it easier to walk towards the front, or the back?

or is it easier to walk east than west?

[SpeckledJim]

singlecoil said:

SpeckledJim said:

1) The person staying still is putting energy into the downward motion of the escalator. He is helping it descend.

2) That energy matches the gain in potential energy of the ascending man.

1) He is applying a force equal to his own weight, he's not 'putting energy' into the escalator.

2) No, it doesn't.

1) Semantics.

2) You keep denying my contentions, but you have still not provided a rebuttal.

If you KNOW that the force applied to the moving escalator is not equal to the gain in potential energy of the climber then just show me HOW you know. Show me the maths.

I am completely open to persuasion here, but seemingly nobody can show me the maths.

[singlecoil]

SpeckledJim said:

singlecoil said:

SpeckledJim said:

1) The person staying still is putting energy into the downward motion of the escalator. He is helping it descend.

2) That energy matches the gain in potential energy of the ascending man.

1) He is applying a force equal to his own weight, he's not 'putting energy' into the escalator.

2) No, it doesn't.

1) Semantics.

2) You keep denying my contentions, but you have still not provided a rebuttal.

If you KNOW that the force applied to the moving escalator is not equal to the gain in potential energy of the climber then just show me HOW you know. Show me the maths.

I am completely open to persuasion here, but seemingly nobody can show me the maths.

1) Not semantics. When you stand on the ground you apply a force to it, but you don't put any energy into it.

2) I checked out of maths when we got to the binomial theorem so I'm not going to be able to show you any maths. But even if I could we would still need to agree on which equations to apply, and we haven't got that far yet.

So, let's see if we can find some areas of agreement as we jointly seek to establish the truth of this matter. First thing I hope we can agree on is that the heavier part of the person A's (person A is the one keeping station on the down escalator) body stays relatively still, and neither gains nor loses height. What say you (on that single point)?

[DJFish]

Hugo a Gogo said:

if you're on a train moving at a constant speed, is it easier to walk towards the front, or the back?

or is it easier t

Depends where the buffet car is located.

Driving home from Scotland is quicker because it's downhill.

[Einion Yrth]

All inertial frames of reference are equivalent; this really isn't up for discussion, at least not without some serious mathematical backup. An escalator, or elevator, or car, bus, aeroplane, swallow (european or african) that is not undergoing acceleration, is in an inertial frame. The equations by which we can predict motion, work, and energy (potential and kinetic) remain the same in any and all inertial frames, this is not news dammit.

Oh, please yourselves.

[Willy Nilly]

Probably one for the high performance car driving PH gods.... Has anyone ever successfully overtaken a Merc Sprinter?

[SpeckledJim]

Einion Yrth said:

All inertial frames of reference are equivalent; this really isn't up for discussion, at least not without some serious mathematical backup. An escalator, or elevator, or car, bus, aeroplane, swallow (european or african) that is not undergoing acceleration, is in an inertial frame. The equations by which we can predict motion, work, and energy (potential and kinetic) remain the same in any and all inertial frames, this is not news dammit.

Oh, please yourselves.

You say it much more persuasively than I.

[Einion Yrth]

SpeckledJim said:

You say it much more persuasively than I.

I fear I am (was) wasting my time. I'm not a physics teacher, and in any event this may be too late in their lives for them to meet one.

[SpeckledJim]

singlecoil said:

SpeckledJim said:

singlecoil said:

SpeckledJim said:

1) The person staying still is putting energy into the downward motion of the escalator. He is helping it descend.

2) That energy matches the gain in potential energy of the ascending man.

1) He is applying a force equal to his own weight, he's not 'putting energy' into the escalator.

2) No, it doesn't.

1) Semantics.

2) You keep denying my contentions, but you have still not provided a rebuttal.

If you KNOW that the force applied to the moving escalator is not equal to the gain in potential energy of the climber then just show me HOW you know. Show me the maths.

I am completely open to persuasion here, but seemingly nobody can show me the maths.

1) Not semantics. When you stand on the ground you apply a force to it, but you don't put any energy into it.

2) I checked out of maths when we got to the binomial theorem so I'm not going to be able to show you any maths. But even if I could we would still need to agree on which equations to apply, and we haven't got that far yet.

So, let's see if we can find some areas of agreement as we jointly seek to establish the truth of this matter. First thing I hope we can agree on is that the heavier part of the person A's (person A is the one keeping station on the down escalator) body stays relatively still, and neither gains nor loses height. What say you (on that single point)?

Relatively still to the ground - yes.

Relatively still to, say, the hips - no. The same small accelerations of the upper body forward and back, up and down, as you make a stride, are present in both cases.

My turn for a simple question:

If it is harder to walk up a stationary staircase than a reversing escalator, because you are gaining height, is it then harder still to walk up an escalator that is moving in the same direction you are, because you are gaining more height?

[singlecoil]

SpeckledJim said:

1) Relatively still to the ground - yes.

2) Relatively still to, say, the hips - no. The same small accelerations of the upper body forward and back, up and down, as you make a stride, are present in both cases.

My turn for a simple question:

3) If it is harder to walk up a stationary staircase than a reversing escalator, because you are gaining height, is it then harder still to walk up an escalator that is moving in the same direction you are, because you are gaining more height?

1) That's good because it's the important point. To raise the height of a weight work has to be done.

2) I agree, but still relatively still to the ground.

3) It's harder to walk up an up escalator that it is to stand still on it, but not harder to walk up one than it is to walk up a static one.

[SpeckledJim]

singlecoil said:

SpeckledJim said:

1) Relatively still to the ground - yes.

2) Relatively still to, say, the hips - no. The same small accelerations of the upper body forward and back, up and down, as you make a stride, are present in both cases.

My turn for a simple question:

3) If it is harder to walk up a stationary staircase than a reversing escalator, because you are gaining height, is it then harder still to walk up an escalator that is moving in the same direction you are, because you are gaining more height?

1) That's good because it's the important point. To raise the height of a weight work has to be done.

2) I agree, but still relatively still to the ground.

3) It's harder to walk up an up escalator that it is to stand still on it, but not harder to walk up one than it is to walk up a static one.

Surely you can see your 3) is a nonsense?

How can an escalator moving in one direction have a measurable effect on a body, which then disappears to zero when you reverse the direction of the movement?

Reverse the movement, reverse the effect, no?

Unless there is no effect...

[MissChief]

I was going to ask a physics questions but then I realised it would just lead to three pages of 'discussion' so I'm off to google it instead.

[SpeckledJim]

MissChief said:

I was going to ask a physics questions but then I realised it would just lead to three pages of 'discussion' so I'm off to google it instead.

Awww, go on....

[Einion Yrth]

MissChief said:

I was going to ask a physics questions but then I realised it would just lead to three pages of 'discussion' so I'm off to google it instead.

Probably wise.

As an edit I'd like to add that it would be nice if you'd ask it anyway, so that us sad bds can squabble about it.

Edited by Einion Yrth on Saturday 30th April 20:47