maths based riddles... See if you can answer them.
Discussion
kVA said:
Wow... there are some patronising people gathering on this thread...
Go and read my answer to the original question - in it's entirety...
If you believe the two are the same, it is you who needs to go and learn about hydrodynamics and aerodynamics
You have been told and shown repeatedly where and why your answer is wrong by several people, and yet you continue to dismiss their input and have so far declined to demonstrate why your answer is correct and theirs isn't.Go and read my answer to the original question - in it's entirety...
If you believe the two are the same, it is you who needs to go and learn about hydrodynamics and aerodynamics
kVA said:
I have sailed upwind in still water many, many times, but I've never been able to beat the tide when there is no wind... it just can't be done.
Well you are sitting on the tide so it's not THAT hard to beat it. If you did a little tiller waggle you would beat it.You realise you aren't trying to head INTO a 10 knot tide right? The tide is with you.
tank slapper said:
You have been told and shown repeatedly where and why your answer is wrong by several people, and yet you continue to dismiss their input and have so far declined to demonstrate why your answer is correct and theirs isn't.
Really?...Someone done the experiment then, have they?
As I said before, a boat floating on a 10 knot current in still air will not travel at 10 knots, so there never will be a 10 knot apparent wind to push the boat backwards.
A boat on still water can tack into a 10 knot breeze and create a much greater than 10 knot breeze on Captain Pugwash's face
A boat floating in a flat calm on a 10 knot current will not be able to travel at 10 knots, even if there is nothing above the water line to create wind resistance... You have clearly never played poo-sticks in your life if you think everything floating in a current travels at the same speed as the water
PS. I do give up now...
Not admitting defeat, but tired of trying to explain basic physics to people who think they have discovered perpetual motion Edited by kVA on Friday 23 September 17:34
kVA said:
Yes I do and go back a few pages to see why this is completely and utterly irrelevant in this puzzle.
I have sailed upwind in still water many, many times, but I've never been able to beat the tide when there is no wind... it just can't be done.
For the sake of the RNLI, please don't try and prove me wrong in a narrow channel - you will need rescuing at some point, unless you are very lucky or have a powerful engine as a back-up.
What do you mean by beat the tide? Do you mean add one or two knots to the almost-10 that the tide is already providing you and ending up where the tide is taking you anyway, but slightly earlier? Or do you mean trying to go somewhere other than where the tide is taking you?I have sailed upwind in still water many, many times, but I've never been able to beat the tide when there is no wind... it just can't be done.
For the sake of the RNLI, please don't try and prove me wrong in a narrow channel - you will need rescuing at some point, unless you are very lucky or have a powerful engine as a back-up.
kVA said:
A boat floating in a flat calm on a 10 knot current will not be able to travel at 10 knots, even if there is nothing above the water line to create wind resistance... You have clearly never played poo-sticks in your life if you think everything floating in a current travels at the same speed as the water
Here we have it.The is ABSOLUTE PROOF that you have literally NO UNDERSTANDING of Newton's first law.
The whole premise of the question is that Boat B is travelling at 10 knots relative to the land.
Yet you deny this.
The fact you can't even grasp this makes continuing the debate laughable.
I have always suspected that you were basing your assumptions on some pathetic misunderstanding about how when you put something STATIONARY in a CURRENT it takes TIME to get up to speed.
Sad.
kVA said:
Not admitting defeat, but tired of trying to explain basic physics to people who think they have discovered perpetual motion
And you were complaining about people being patronising. This has nothing to do with perpetual motion for about the 20th time. It comes down to the fundamental reason a sailing boat works - the ability to extract energy from a difference in velocity between the flow of air over the sails and the flow of water over the hull. If there is a difference, hence an external source of energy, the boat can sail. It matters not whether the difference arises from movement of the air, movement of the water or a combination of both.If there is no difference, there is no energy input and the boat can't sail. If there is a difference, there is an energy input and the boat can sail.
kVA said:
Incidentally, I note that the original objectors to my theory have gone awful quiet? have you just realised I'm right at last?
You have bunny hopped around kVA said:
I repeat - Newton's Third Law of momentum: Every action must have an equal and opposite reaction
(page 22, if you've forgotten) to weight, mass, aerodynamic drag, hydrodynamic drag, inertia, gravity, gravtational inertia, the surface of the water being curved, perpetual motion, and no doubt a host of other expressions that I've long since forgotten.
You asked for a physics professor to turn up and give a definitive answer. When you were referred to a University paper, you said it was wrong. You refuse to listen or debate this puzzle because you claim that you know you are right.
Despite being cocky and patronising, walm has spent more time than it is right or proper to spend trying to help you unravel the muddle in your head. You resolutely refuse to listen.
So it is rather silly to claim that quiet signifies your triumph. One might as well say that your departure on holiday was an admission of defeat by you.
tank slapper said:
And you were complaining about people being patronising. This has nothing to do with perpetual motion for about the 20th time. It comes down to the fundamental reason a sailing boat works - the ability to extract energy from a difference in velocity between the flow of air over the sails and the flow of water over the hull. If there is a difference, hence an external source of energy, the boat can sail. It matters not whether the difference arises from movement of the air, movement of the water or a combination of both.
If there is no difference, there is no energy input and the boat can't sail. If there is a difference, there is an energy input and the boat can sail.
this may all be true, but the puzzle attempts to prove some "amazing" point without taking into account al the factors around sailing. If there is no difference, there is no energy input and the boat can't sail. If there is a difference, there is an energy input and the boat can sail.
you can't set something difficult and discount half the forces involved- just cherry pick the points you like.
That's what academics do when they prove that bumble bees can't possible fly. If you go out in the real world and try this it doesn't work. The only time it could work is in a set of circumstances so unlikely they can be discounted as impossible.
Those of us saying the original proviso is wrong, are not denying that you can sail into an apparent wind- you can. its just NOT quicker in the real world than the other option.
PugwasHDJ80 said:
this may all be true, but the puzzle attempts to prove some "amazing" point without taking into account al the factors around sailing.
you can't set something difficult and discount half the forces involved- just cherry pick the points you like.
That's what academics do when they prove that bumble bees can't possible fly. If you go out in the real world and try this it doesn't work. The only time it could work is in a set of circumstances so unlikely they can be discounted as impossible.
Those of us saying the original proviso is wrong, are not denying that you can sail into an apparent wind- you can. its just NOT quicker in the real world than the other option.
Please point out which forces have been cherry picked, and which discarded. Which factors have not been taken into account?you can't set something difficult and discount half the forces involved- just cherry pick the points you like.
That's what academics do when they prove that bumble bees can't possible fly. If you go out in the real world and try this it doesn't work. The only time it could work is in a set of circumstances so unlikely they can be discounted as impossible.
Those of us saying the original proviso is wrong, are not denying that you can sail into an apparent wind- you can. its just NOT quicker in the real world than the other option.
No academic has ever set out to prove a bumblebee can't fly. That would be stupid, as they clearly can fly. A bit like arguing a sailing boat can't sail into an apparent wind, when they quite obviously can.
PugwasHDJ80 said:
tank slapper said:
And you were complaining about people being patronising. This has nothing to do with perpetual motion for about the 20th time. It comes down to the fundamental reason a sailing boat works - the ability to extract energy from a difference in velocity between the flow of air over the sails and the flow of water over the hull. If there is a difference, hence an external source of energy, the boat can sail. It matters not whether the difference arises from movement of the air, movement of the water or a combination of both.
If there is no difference, there is no energy input and the boat can't sail. If there is a difference, there is an energy input and the boat can sail.
this may all be true, but the puzzle attempts to prove some "amazing" point without taking into account al the factors around sailing. If there is no difference, there is no energy input and the boat can't sail. If there is a difference, there is an energy input and the boat can sail.
you can't set something difficult and discount half the forces involved- just cherry pick the points you like.
That's what academics do when they prove that bumble bees can't possible fly. If you go out in the real world and try this it doesn't work. The only time it could work is in a set of circumstances so unlikely they can be discounted as impossible.
Those of us saying the original proviso is wrong, are not denying that you can sail into an apparent wind- you can. its just NOT quicker in the real world than the other option.
kVA said:
I'm back 
Thanks for your patronising post, deeen: I do understand Newton's 3rd Law and I know it doesn't mention perpetual motion, but it does say that every action must have an equal and opposite reaction... All the well meaning folks on here that think I am wrong are conveniently forgetting the reaction of the 'apparent wind' on the boat's speed: If you exert a force on anything floating in a current, you will affect it's speed relative to the land (and the water). In this riddle, the apparent wind is always in the opposite direction to the current (by definition) and so will slow the boat down - reducing the apparent wind-speed in the process. You are also conveniently ignoring gravity!!! The heavier something is, the easier it is for some of the water to slip past it, rather than push it along at the same speed - especially something specifically designed to be smooth and slippery underneath, precisely so that water can easily slip past it and allow unimpeded forward motion: If the boat always moved at the same speed as the current, regardless of weight, logging in Canada would be a seriously dangerous occupation for those guys that stand on them in the fast flowing rivers!!!
I will stand by my opinion that boat B will win this race, as, unless boat A has zero aerodynamic drag (in which case it will be a draw), any other solution will contradict the basic laws of physics - it just cannot be done.
You would be right if both boats stayed stern to current (head to wind).Thanks for your patronising post, deeen: I do understand Newton's 3rd Law and I know it doesn't mention perpetual motion, but it does say that every action must have an equal and opposite reaction... All the well meaning folks on here that think I am wrong are conveniently forgetting the reaction of the 'apparent wind' on the boat's speed: If you exert a force on anything floating in a current, you will affect it's speed relative to the land (and the water). In this riddle, the apparent wind is always in the opposite direction to the current (by definition) and so will slow the boat down - reducing the apparent wind-speed in the process. You are also conveniently ignoring gravity!!! The heavier something is, the easier it is for some of the water to slip past it, rather than push it along at the same speed - especially something specifically designed to be smooth and slippery underneath, precisely so that water can easily slip past it and allow unimpeded forward motion: If the boat always moved at the same speed as the current, regardless of weight, logging in Canada would be a seriously dangerous occupation for those guys that stand on them in the fast flowing rivers!!!
I will stand by my opinion that boat B will win this race, as, unless boat A has zero aerodynamic drag (in which case it will be a draw), any other solution will contradict the basic laws of physics - it just cannot be done.
The other boat wins the race by tacking into the 10 knot headwind. This is proved possible within the "laws of physics" by boats tacking into 10 knot winds every day, the sails only "see" the apparent wind, they do not know how it is generated.
Gravity is not relevant as it acts directly downwards. The logs are slower because of momentum, and friction from the environment.
Action / reaction - the relevant action is the wind creating lift in the sails once they are filled correctly, the net reaction (because of the shape of the hull) is the boat moving forward through the water, as with every boat tacking every day. Yes the boat does have aerodynamic drag, but it's insignificant (at 10 knots) compared to the force the sails can generate. That's why all those tacking boats actually move forwards.
If you still don't agree, would you like to quote exactly which law of physics this contradicts?
PugwasHDJ80 said:
this may all be true, but the puzzle attempts to prove some "amazing" point without taking into account al the factors around sailing.
you can't set something difficult and discount half the forces involved- just cherry pick the points you like.
That's what academics do when they prove that bumble bees can't possible fly. If you go out in the real world and try this it doesn't work. The only time it could work is in a set of circumstances so unlikely they can be discounted as impossible.
Those of us saying the original proviso is wrong, are not denying that you can sail into an apparent wind- you can. its just NOT quicker in the real world than the other option.
How can sailing forwards through the water be slower than not sailing forwards through the water?you can't set something difficult and discount half the forces involved- just cherry pick the points you like.
That's what academics do when they prove that bumble bees can't possible fly. If you go out in the real world and try this it doesn't work. The only time it could work is in a set of circumstances so unlikely they can be discounted as impossible.
Those of us saying the original proviso is wrong, are not denying that you can sail into an apparent wind- you can. its just NOT quicker in the real world than the other option.
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