Re: [math-fun] Another physics question
<< The idea was to give a time-independent example of energy, but explaining the difference between mass and weight may not be clear to beginners, especially why acceleration has to be involved.
One pedagogic loophole the keeps acceleration only implicit, would be to define work (energy E) as determined by the time t it takes to bring a (frictionless) body of mass m up to speed s (along a straight line): E = ms/t. This has a visceral aspect to it, always a good thing in teaching. --dan
Huh? I might believe force F = ms/t (for constant acceleration), then multiply by distance traveled (1/2 st), giving E = 1/2 m s^2, the usual (non-relativistic) formula for kinetic energy. --ms dasimov@earthlink.net wrote:
<< The idea was to give a time-independent example of energy, but explaining the difference between mass and weight may not be clear to beginners, especially why acceleration has to be involved.
One pedagogic loophole the keeps acceleration only implicit, would be to define work (energy E) as determined by the time t it takes to bring a (frictionless) body of mass m up to speed s (along a straight line): E = ms/t. This has a visceral aspect to it, always a good thing in teaching.
--dan
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Or tie the two together by dropping the same block from a known height onto the table via a 90 degree smooth curved chute to losslessly change vertical motion to horizontal, and let the table have a known coefficient of friction, and see how far the block goes. This introduces, more or less painlessly, potential energy, kinetic energy, energy dissipation through friction. Then you can plot drop height vs. distance moved on the table, etc. There are probably actual school experiments of this type. Steve ----- Original Message ----- From: <dasimov@earthlink.net> To: "math-fun" <math-fun@mailman.xmission.com> Sent: Tuesday, July 18, 2006 1:28 PM Subject: Re: [math-fun] Another physics question
<< The idea was to give a time-independent example of energy, but explaining the difference between mass and weight may not be clear to beginners, especially why acceleration has to be involved.
One pedagogic loophole the keeps acceleration only implicit, would be to define work (energy E) as determined by the time t it takes to bring a (frictionless) body of mass m up to speed s (along a straight line): E = ms/t. This has a visceral aspect to it, always a good thing in teaching.
--dan
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
There are probably actual school experiments of this type.
My high school had ramps between wings, and a standard experiment in physics was to calculate G by timing golf balls rolling down the ramp. The trick was, they hadn't covered angular momentum yet, so the "experiment" was actually to see who was willing to fudge their numbers to make the answer come out right.
They could have gotten around that by using a wheeled contraption where the weight did not rotate (needs bearings), or where almost all the weight was very close to the axis. I hope at least you got a gold medal in fudging! SG ----- Original Message ----- From: "Dave Dyer" <ddyer@real-me.net> To: "math-fun" <math-fun@mailman.xmission.com>; <dasimov@earthlink.net>; "math-fun" <math-fun@mailman.xmission.com> Sent: Tuesday, July 18, 2006 2:20 PM Subject: [math-fun] Re: Another physics question
There are probably actual school experiments of this type.
My high school had ramps between wings, and a standard experiment in physics was to calculate G by timing golf balls rolling down the ramp.
The trick was, they hadn't covered angular momentum yet, so the "experiment" was actually to see who was willing to fudge their numbers to make the answer come out right.
participants (4)
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dasimov＠earthlink.net -
Dave Dyer -
Mike Speciner -
Steve Gray