Is it possible to measure gravitational acceleration 'g' near the earth's surface using a centrifuge? Someone told me that if you put a small object like a pebble in a centrifuge, start the centrifuge off at a high speed, and slowly lower the angular speed. At the speed the pebble falls out, the gravitational acceleration will equal omega squared times r (radius); is this valid? (omega is angular speed, the derivate of the angle with respect to time, or 2pi radians/period if angular speed is constant)
I do not think so, because the force here is the frictional force between pebble and centrifuge, and not the gravitational force.
Also, If you swing anything in a vertical, circular pattern, anything inside of it will experience two forces at the top of the arc. If the measurable, centrifugal force is less than the force of gravity, the object will fall. Is this correct? If so, can this be used to measure 'g'?
If not, is there a way to measure 'g' using a centrifuge? Thank-you.
2007-07-23 09:08:12 · 4 answers · asked by qspeechc 4 in Science & Mathematics ➔ Physics
if the centrifuge were frictionless then yes it is possible. At a certain angular velocity the centripetal force will be less than that of gravity and then the pebble will fall out. I'd have to look up the formulae for calculating forces due to circular rotation but it could definitely be done. It is a lot easier to do it with a pendulum. Again I forgot the formulae but the period of a pendulum is a function of its length and gravity. I hope that helps.
2007-07-23 09:14:44 · answer #1 · answered by imunalia 3 · 0⤊ 0⤋
Yes, the measurement can be made, but in a much less complicated manner.
Allow the object to pivot on the end of the centrifuge arm.
With G being the downward force, and C being the centrifugal force, when G and C are equal the object will have pivoted 45 degrees. If the speed is known C and thus G are known.
2007-07-23 10:41:05 · answer #2 · answered by Irv S 7 · 0⤊ 0⤋
"If you swing anything in a vertical, circular pattern, anything inside of it will experience two forces at the top of the arc. If the measurable, centrifugal force is less than the force of gravity, the object will fall. Is this correct? If so, can this be used to measure 'g'?"
This is exactly the case to which your friend actually referred to (something like cloth dryer).
g = ω² R
2007-07-23 09:30:57 · answer #3 · answered by Alexander 6 · 0⤊ 0⤋
yes.
2016-05-21 03:22:00 · answer #4 · answered by juanita 3 · 0⤊ 0⤋