Seeing the difference between kinetic energy and momentum, with wheels.
Here's a fresh take on the spinning chair experiment, by showing
conservation of angular momentum, and also how kinetic energy changes. Momentum is proportional to velocity, and kinetic energy to velocity
squared, as per teaching.
The Physics Textbook, University Physics, Young and Freedman,
Global Edition, 15th Edition page 348 has the angular momentum conservation,when you hold out dumbbells when spinning, and you bring
your arms in. You go much faster, as proveable science fact.
The increase in work is given by the expenditure of muscle energy from
the arms. It isn't a scientific measurement, just a glib take it
explanation. Need a quantitative meaurement.
So I'm suggesting to have a 1m radius wheel with 2x5kg weights at the
end of spokes, which are also rails. For the work to bring in the
weights use a dropping a weight or weight in the centre. Easier
calculations if the dropped weight isn't spinning, but more tricky
gearing.
Obviously the only increase in energy should be from the the dropped
weight and I do believe in mgh for energy for a mass to move things up.
However there is a lack of hard evidence about kinetic energy being proportional to velocity squared. As the weights are moved inwards by
the known energy of the dropped weight, if there is an additional
increase because of the higher velocity, obviously there is a theory
matter to be resolved, at the school and undergraduate level for what is being taught to everyone.
If you're only interested in hard science fact, you can safely end
reading here.
There are fairground caurousel rides with this type of thing,
which about 1900, was probably a known alegory, but this type of
knowledge is all lost to history. Education is becoming a hotter topic
in the UK now. As stated kinetic energy proportional to velocity squared
is the hardest topic to get children to learn. It's either a problem
with what is taught or how it's taught.
On 24 40, Dave wrote:
Seeing the difference between kinetic energy and momentum, with wheels.
Here's a fresh take on the spinning chair experiment, by showing
conservation of angular momentum, and also how kinetic energy changes.
Momentum is proportional to velocity, and kinetic energy to velocity
squared, as per teaching.
The Physics Textbook, University Physics, Young and Freedman,
Global Edition, 15th Edition page 348 has the angular momentum
conservation,when you hold out dumbbells when spinning, and you bring
your arms in. You go much faster, as proveable science fact.
The increase in work is given by the expenditure of muscle energy from
the arms. It isn't a scientific measurement, just a glib take it
explanation. Need a quantitative meaurement.
So I'm suggesting to have a 1m radius wheel with 2x5kg weights at the
end of spokes, which are also rails. For the work to bring in the
weights use a dropping a weight or weight in the centre. Easier
calculations if the dropped weight isn't spinning, but more tricky
gearing.
Obviously the only increase in energy should be from the the dropped
weight and I do believe in mgh for energy for a mass to move things
up. However there is a lack of hard evidence about kinetic energy
being proportional to velocity squared. As the weights are moved
inwards by the known energy of the dropped weight, if there is an
additional increase because of the higher velocity, obviously there is
a theory matter to be resolved, at the school and undergraduate level
for what is being taught to everyone.
If you're only interested in hard science fact, you can safely end
reading here.
As there are many ways to cook eggs, it may be better to use the angular momentum to move the weights in, and see what happens when you check
closely, as you do. If you can get the calculated kinetic energy to increase there is obviously a problem because free energy devices aren't
so easily made.
Wrap a piece of string around the axle, or something similar to move the weights. Then let it out again. There will be some who'll say there's elasticity in the string, and the latch movement is the cause, but then repeat several times and see what they say. Govenors from big steam
engines would be somewhat similar, with an opposite effect.
There are fairground caurousel rides with this type of thing,
which about 1900, was probably a known alegory, but this type of
knowledge is all lost to history. Education is becoming a hotter topic
in the UK now. As stated kinetic energy proportional to velocity squared
is the hardest topic to get children to learn. It's either a problem
with what is taught or how it's taught.
Angular momentum remains tge same but rotational ke changes when a
rotating body spreads in or out like stretching in or out the arms.
bertietaylor wrote:
Angular momentum remains tge same but rotational ke changes when a
rotating body spreads in or out like stretching in or out the arms.
So consider a spinning ballerina (doing that without friction loss)
with arms in. She has moment of inertia I1 and rotational speed w1.
So her angular momentum is I1w1.
Now she stretches her arms out so she has a different moment of
inertia I2, more than earlier. She slows down to speed w2 and as per
the law of conservation of angular momentum, we have
I1w1=I2w2
Now her kinetic energies before and after were 0.5I1w1^2 and
0.5I2w2^2. By the law of conservation of energy, they should be equal.
But we will will that will violate the law of conservation of angular momentum!
The law of conservation of angular momentum can be proved by
experiment, knowing I1, w1 and I2 and calculating w2 from there and
then checking whether it matches the measured w2.
So it is that Arindam is again vindicated. The law of conservation of
energy is at best a special case. The ballerina violates that easily!
Energy is created and destroyed endlessly in our infinite universe.
woof woo
Bertietaylor (Arindam's ghostly cyberdoggies and his best friends)
teaching the e=mcc thumper-chanters a basic lesson in Arindamic
physics.
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