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btw, have you never seen people Sorbing?
Quote from: sophiecentaur on 22/03/2009 20:19:10btw, have you never seen people Sorbing?Like Liza it's with a "zee" ... http://www.zorb.com/main.htmlThey throw a bucket of water* in the Zorb with the passengers: it must be like being in a washing machine.[* Maybe this preemptive soaking is to make washing the vomit out easier]
I don’t agree with the mud though, nothing dripped off when I did a little simulation with a thick knife aka ring.
Dewed grass won’t touch the mesh either as it is too short,
Somebody told me my rolling resistance should be orientated in the opposite direction acting from the bottom of the wheel in order not to contribute to the rotation of the wheel. I find this very confusing;http://webphysics.davidson.edu/faculty/dmb/PY430/Friction/rolling.html-> The first diagram agrees with the above because the wheel is not rolling yet. But down the bottom of the page there’s “distribution of the normal forces creates a net torque negating the rotational contribution of the friction” ?http://cnx.org/content/m14385/latest/-> Here the formulas are completely different (no rolling resistance coefficient) and there’s no deformation.
I think the confusion may arise because of Newton's Third Law and the need to choose the appropriate "action" or "reaction" force.
A treadmill is a mill consisting of a large wooden cylinder with steps on the outside. It is worked by persons treading on the steps, their weight causing the cylinder to revolve. The treadmill was invented in China and originally used for raising water. The treadmill employed in British prisons as an instrument of torture or punishment was invented by Sir William Cubitt. The first penal treadmill was erected in Brixton Jail in 1817. The 'hard labour' of prison discipline was formerly the treadmill.
If the wheel was on a hard surface, (human-hamsterwheel isn't), the only "resistance" to rotation is from its moment of inertia.
sophiecentaur: Thanks for your diagrams! Assuming your last diagram is the correct one, how would you calculate where the origin of the rolling resistance force is?Continuing the quote from the guy at Physicsforums: “The rolling resistance force is (mw + mp)*g. The rolling resistance moment is (mw + mp)*g*b. If you compute a horizontal force couple at the wheel centre and ground necessary to overcome this rolling resistance moment, then the force is F = [(mw + mp)*g*b]/r, pointing forward at the wheel centre, and backward at the ground.”
RD: So playgrounds and gyms are for torture and punishment?