(John Schilling) writes:

"Wim Dekker" writes:

"Mike Miller" wrote in message
m...
DP wrote in message
...

That's a bit different than Jovian atmosphere re-entry. Like,
a lot slower. Cassini's RTGs were expected to (IIRC) burn off
33% of their mass if Cassini hit Earth during its sling shots
past Earth. Cassini swung by Earth at 19km/s. Galileo hit Jupiter
at 48km/s. 2.5 times the entry velocity translates into 6.25
times the kinetic energy to be converted into heat per kilogram
of spacecraft.

I don't understand why kinetic energy increases quadratically
with speed while the energy it costs to increase speed itself
seams to be directly proportional to the speed. After all,
speed = acceleration * time. What's wrong with my reasoning?

The implicit assumption that acceleration is proportional to
energy or power. In fact, power = acceleration * velocity,

Um, I'm sure it's just a typographical omission, but that should read:

power = mass * acceleration . velocity.

(from Power = F.v). Which is why:

when you do the integral you do get energy = 1/2 * mass * velocity^2.


-- Gordon D. Pusch

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