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Re: Frames of Reference



Message text written by INTERNET:phys-l@atlantis.uwf.edu
Does the physicist, checking for momentum conservation in a bubble
chamber
photograph, worry about the earth providing a moving frame of reference=

or do they operate as we do in a conventional lab, assume the lab is an=

inertial frame?

He doesn't have to. The quantity which is important in collisions is the=

impulse exchanged. These interactions take place over such a short time
that any impulse due to gravitational forces is utterly unobservable,
though the gravitational forces are in principle quite observable.

That's a good problem to give your students, however. Many will say "The=

gravitational force is just too small to matter". That is not the case, =
of
course. If the particles stuck around for a tenth of a second in the spa=
rk
chamber they would fall just as far as a tennis ball in the same time. T=
he
question will test whether or not they are thinking.

Leigh


Do the calculation Leigh. In bubble chambers most particles travel
at v > 0.99c. For a 10 m chamber I get a drop of about 10^14 m - very =

unobservable. (They hang around for about 3 x 10^-8 s.)

Bill Larson
Geneva