oldton wrote:
why is work defined as F.S ??
plz help quickly
Because it was discovered that it works.
Conservation of energy is not a *definition*. It was an interesting
fact that was *noticed* about nature.
It turns out that if you calculate certain numbers from measurable
properties of a closed physical system, and add those numbers up, the
total always ends up staying constant, even if something is physically
going on inside the system to change the values of those measured
properties. It's quite a spectacular thing that, even though the parts
of the system are interacting, bouncing back and forth, stretching,
deforming, changing temperature, that the sum of all those
contributions (which we call the energy) ends up not changing at all.
That's what made physicists take notice and write down, "Remember how
to calculate this number. It is useful."
Now, the various contributions to the energy depend on the properties
of the system. For example, for something that is moving with respect
to some reference point, then the way to calculate that contribution
(so that the total ends up staying the same) is (1/2)mv^2 (as long as
the something does have mass and as long as it's not moving too fast --
if either of those isn't true, we have to calculate it a slightly
different way).
The way to calculate the contribution to the energy from an external
force is F.s.
Now, we can make all sorts of plausibility arguments about why it's
likely that this contribution should be calculated this way and another
contribution should be calculated that way, but the bottom line is: we
know this is the way to calculate it because when we do, the sum stays
constant. That is, because it works.
ok thanx
is the inertia(rotational) of a particle about a pt L away being mL^2
similar??
i mean it was probably 'discovered' that angular accleration varies
linearly with such a quantity... but then why was torque "defined" as f
x d(or was it). can u explain it to a few layers of "why"s.
thanking u
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