Originally posted by smomofoSounds like a reasonable experiment. Did you keep the numbers?
I guess I don't look at things in quite the detail some of you do. For me, the fact that after the water is poured from the kettle, the kettle is still hot to the touch is enough evidence for me to find it reasonable that not all of the energy supplied to the kettle went into the water.
The experimental procedure is roughly:
1) Measure the mass of a dry ...[text shortened]... erature of water after heating
7) Measure current and voltage supplied to kettle while heating
Originally posted by doodinthemoodThe plane is only going to take off if the airspeed around the wings gets to a critical value, or if the plane is propelled somehow (propellers, jet propulsion, etc...). If a non-propelled plane with freely rotating wheels is placed on a treadmill, the wheels will spin but the plane's wings won't be moving against the air any faster than before so it will stay put.
But that's what makes it so good. It's very hard not to follow your gut and say it doesn't. Which makes it fit this topic. The reality is that it would take off.
Originally posted by PBE6Continue to discuss this (damn) aeroplane in it's original thread - pleazzze...!ðŸ˜
The plane is only going to take off if the airspeed around the wings gets to a critical value, or if the plane is propelled somehow (propellers, jet propulsion, etc...). If a non-propelled plane with freely rotating wheels is placed on a treadmill, the wheels will spin but the plane's wings won't be moving against the air any faster than before so it will stay put.
Originally posted by doodinthemoodFeel free to find the previous thread - you'd be amazed how much discussion and disagreement the phrase "at the same speed as the plane" can cause.
But that's what makes it so good. It's very hard not to follow your gut and say it doesn't. Which makes it fit this topic. The reality is that it would take off.
Originally posted by agrysonhmm...this might sound a bit daft but is it really reasonable to expect that the tyres and treadmill could ever create enough frictional force to prevent the plane's forward movement under jet propulsion???
Go on doodinthemood, give us the worked answer, I have to admit that excluding strong winds, my gut says it won't take off, jet propulsion or not. What's the reasoning behind a 'yes it will take off answer'?
Originally posted by agrysonVery simple. Power comes from the jets not the wheels. Plane travels forwards at 200mph, treadmill goes backwards at 200mph, the wheels spin at 400mph but the plane still goes forwards. It takes off normally.
Go on doodinthemood, give us the worked answer, I have to admit that excluding strong winds, my gut says it won't take off, jet propulsion or not. What's the reasoning behind a 'yes it will take off answer'?
Regarding the riddle-chimp puzzle, strictly speaking it needn't require any prizegiving whatsoever. After all, the chimp only says that he will "ask you to say a statement" -- he doesn't specify that YOU get to choose the statement. He may instead ask you to repeat a statement, or to read one from a card. What if he asks you to read a "paradoxical" statement -- or if you don't buy that, then how about a statement with no evaluatable truth value: perhaps it makes an empirical claim that cannot be verified or disproven a priori (and a posteriori it cannot be evaluated because it refers to a past event that wasn't observed and will never repeat, or to a hypothetical future event which may not ever occur). Or a statement that has no evaluatable truth value because it is unresolvably ambiguous and the different interpretations have different truth values. Or even a statement which has no meaningful interpretation (e.g., "blond cats waffle therapy obtusely"😉.
Then there is the fact that (apparently) the sole arbiter of the contest is the riddle-chimp; and there is nothing in the puzzle as stated indicating that the riddle-chimp is either truthful or unerring. He may not even be sentient. Perhaps he's a defective cyborg with no mind at all whose virus altered programming causes him to take an ax to anyone agreeing to "say a statement".
I'm not putting that smiley-face in and I can't seem to edit it out.
Originally posted by doodinthemoodI agree, the jet/prop pushes back on stationary AIR. The wheels roll twice as fast as the plane moves and it takes off normally. I think they actually covered this on the straight dope.
Very simple. Power comes from the jets not the wheels. Plane travels forwards at 200mph, treadmill goes backwards at 200mph, the wheels spin at 400mph but the plane still goes forwards. It takes off normally.
Originally posted by Mark AdkinsActually you did, but you didn't know how or when.
I'm not putting that smiley-face in and I can't seem to edit it out.
When using the characters ; and ) together, the editor change it into 😉 automatically.
Try it youself and you'll see.
You can easily get rid of the face by finding the ; and ) and delete the two characters, or putting an extra space in between.
Pondering the Monty Hall problem, and I came to a conclusion on it.
The setting is as follows (for those who haven't heard it.)
You're on a game show, and are shown 3 doors, only one of which has a prize. After you select a door, the host opens one of the other two doors, which ends up being empty (or alternatively having a dummy prize of little value)
The question is: Are you better off switching, or staying? Or does it even matter?
Now, in the original problem, the host knows which door is the winning door, and always selects a losing door.
Now many would argue that it doesn't matter if you switch or stay, you're odds are 50/50 either way. However, this reasoning is faulty because the game host is assured of opening a losing door, because he knows which one is the winner, and won't pick it. So if you stay with your original door, you'll only be right 1/3 of the time, and you should have switched the other 2/3 of the time.
However, suppose the host DIDN'T know which one held the prize, and still chose an empty door. Or suppose he selected a random audience member and let them pick the door to open and it was empty?
In that case, it wasn't assured that the selected door was a losing door, and as such, you can eliminate some possibilities you couldn't before.
As it ends up, the odds are 50/50 either way.