Re: Momentum Question



George wrote:
> Hi,
> This question could be stupid so be patient,
> Space shuttle weighs 59000 pounds on earth, now if in space, zero
> gravity a person tied to stationary shuttle spits will spitting give
> enough momentum for shuttle to move ,

Already answered: whether on earth or in space, a
person tied to (the outside of the shuttle) and
spitting has the same effect as a rocket: it imparts
a small momentum to the shuttle. But on earth friction
with the ground counters this momentum.

> The related question is out sun is expelling mass at tremendous
> velocity so why doesn't it act like rocket and shoots off in space,

It does. But the mass ejected is very small compared to
the mass of the sun. Work it out. The resulting perturbations
in the sun's motion would be microscopic. Do you think you
really could tell if the sun's velocity changed by,
say, 0.00001 mm/sec for a few seconds, till the next
burst?

The earth too experiences changes in momentum, every
time a rocket is launched, a person jumps, or a
meteor strikes the atmosphere. But the resulting
changes in momentum are too small to be measurable,
even from something as massive as a nuclear explosion.

Planets are BIG.

> it
> could be that since its spherical shape nullifies the ejection as it
> happens al around but is the ejection same in all direction

On average over a long period of time, yes. But over
short periods of time there will be slight asymmetries
and so there would be slight resultant forces.

- Randy

.

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