[Phys-l] First law and balanced forces Was: Re: [PTSOS] anvil and sledgehammer inertia demo

[Bernard Cleyet <bernardcleyet@redshift.com>]

An electric powered fanned cart w/ a friction pad would be the automobile in the room demo.  One may vary the power to the fan and the force on the pad to show constant motion w/ various balanced forces.   An ultrasonic ranger or linearized angular encoder would serve for quantitative illustration.

bc thinks the balanced Atwood's machine is fine for the cash strapped.

p.s.  Often used in HS physics is gee whiz demos, e.g. the anvil on the tummy.  It's unfortunate that such apparently is necessary to keep the students interested, which is essential for any learning.

On 2010, Sep 29, , at 12:26, ludwik kowalski wrote:

> On Sep 29, 2010, at 3:15 PM, Stefan Jeglinski wrote:
>
> > > The really important demo is to show that a moving object
> > > with balanced forces remains in constant motion.
> >
> > I substantially agree. What are your favorite demos of this, suitable
> > for a classroom?
>
> The first thing that came to my mind was driving a car horizontally. I press the gas pedal too strongly and the car accelerates; I press it much less strongly and the car slows down.
>
>
> http://csam.montclair.edu/~kowalski/life/intro.html
>
>
>
>
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