Power = work / time. Time = 1, so here power = work.
Work = Distance * Force. Distance = 9 so Work = 9*Force
Force = Mass(Acceleration). Acceleration = 10 (gravity.) Mass = 60 (600 is weight -> /10 and 60 is mass). Force = 600.
So Work = 9*600, Work = 5400. Power = 5400. Done. (Isn't that a bit more simple, just use the Force = Mass * Acce ...[text shortened]... e still have #1-#2. (tension is the other variable in #10). Then I'll post the hardest I know.
You could simply look at the texture of the ground.
now...
Originally posted by Restless Soul if the lawn was blue airplanes wouldn't know where to land
Blue flowers are not pollinated by insects.
Because if insects would be attracted to the blue colour, then they would fly to the sky.
Can anyone entomologist/botanist confirm this?
Originally posted by FabianFnas Blue flowers are not pollinated by insects.
Because if insects would be attracted to the blue colour, then they would fly to the sky.
Can anyone entomologist/botanist confirm this?
Some bee flowers tend to be yellow or blue, often with ultraviolet nectar guides and scent.
Originally posted by Ramned tension is the other variable in #10
You missed one - where you pluck it. That determines which harmonics the string vibrates at. E.g. compare plucking it in the middle with plucking it a quarter of the way along.
Originally posted by mtthw You missed one - where you pluck it. That determines which harmonics the string vibrates at. E.g. compare plucking it in the middle with plucking it a quarter of the way along.
tension covers that. The edges are more tense than the middle = tension.
So, #1-#2 - who knows those tricky mirror questions?
Originally posted by Ramned tension covers that. The edges are more tense than the middle = tension.
No it doesn't. The tension is the same everywhere (neglecting some minor effects like gravity). Think about balancing the forces on a section of the string - the forces at each end (in other words the tension at each end) must cancel out. This applies to any section of string, so the tension is constant.
Pluck a string in the middle and you get the first harmonic. Pluck it a quarter of the way along and you'll get the second harmonic - half the wavelength and twice the frequency. Pluck it somewhere in between and you'll get a mixture of harmonics.
Originally posted by mtthw No it doesn't. The tension is the same everywhere (neglecting some minor effects like gravity). Think about balancing the forces on a section of the string - the forces at each end (in other words the tension at each end) must cancel out. This applies to any section of string, so the tension is constant.
Pluck a string in the middle and you get the first ...[text shortened]... nd twice the frequency. Pluck it somewhere in between and you'll get a mixture of harmonics.
It's true! I've popped many a squealie in my lifetime.
Originally posted by mtthw Pluck a string in the middle and you get the first harmonic. Pluck it a quarter of the way along and you'll get the second harmonic - half the wavelength and twice the frequency. Pluck it somewhere in between and you'll get a mixture of harmonics.
Unless you can pluck the string in such a way that just before you let go it is shaped exactly like a sine wave then you won't get a pure harmonic no matter where you pluck it; although how important each harmonic is is going to depend on where it's plucked.
I double checked the statement about tension on Wikipedia before posting and couldn't find any statement to contradict what we are saying about it being uniform along the string, but while I was looking I found this:
http://en.wikipedia.org/wiki/Vibrating_string
Which gives a nice puzzle for the thread. Why is the derivation of the speed of waves on the string wrong? And why does the author happen to get the right answer?
Originally posted by DeepThought Unless you can pluck the string in such a way that just before you let go it is shaped exactly like a sine wave then you won't get a pure harmonic no matter where you pluck it; although how important each harmonic is is going to depend on where it's plucked.
I double checked the statement about tension on Wikipedia before posting and couldn't find any ...[text shortened]... speed of waves on the string wrong? And why does the author happen to get the right answer?
True, I was simplifying.
As for the last bit - well spotted! Centripetal force for something that isn't rotating? I don't think so. Dimensional analysis tells you the answer is going to be right to within a constant multiplier though. Which happens to be 1, though that may be coincidence.
I see, I did oversimplify tension. I should have said that if you were to pluck the string in the same place everytime, tension and length would be the factors for the pitch.
07 Jun '07 11:391 edit
Physics Test - how smart are you?
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