Releasing stored energy

[Lino Verna]

I think we are all closing in on a conclusion, pretty soon we won't need
these
cone shaped hats any more.   Any one else having trouble going through
doors?


>Inertia is a property of matter. I don't remember doing calculations to
figure the
>amount of inertia a system had or units of
>inertia.  Now, momentum is another thing.

Momentum of an object is its mass times its velocity


>A block is a distance Y above the ground and is released.
>At time 0:
>Potential energy = gravity x Y = gY

You forgot the mass.    PE = mgh  or mgy in the above example

The best example I can remember is a pendulum.  At the end of its swing
it has zero velocity, so all its energy is potential.  It can be calculated
by multiplying its mass by g and by its height relative to the bottom of its
swing.

Then at the bottom of the swing it has no potential energy (assuming the arm
cannot break)  all its energy is in its motion.  Calculated by 1/2mv^2.

The neat thing about it is that (aside from minor losses) the potential
energy
at the end of the swing is equal to the kinetic at the bottom.  And at any
point in the swing  the sum of the kinetic and potential energies is also
equal to the value at either the top or the bottom.

So, thank god, energy is conserved.  Always.

lino

ps  A man wearing a cone shaped hat walks into a bar and says ouch.