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rolling resistance

n. (context physics English) The force that resists the rolling of a wheel or other circular object.

Wikipedia
Rolling resistance

Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc. is recovered when the pressure is removed. Two forms of this are hysteresis losses (see below), and permanent (plastic) deformation of the object or the surface (e.g. soil). Another cause of rolling resistance lies in the slippage between the wheel and the surface, which dissipates energy. Note that only the last of these effects involves friction, therefore the name "rolling friction" is to an extent a misnomer.

In analogy with sliding friction, rolling resistance is often expressed as a coefficient times the normal force. This coefficient of rolling resistance is generally much smaller than the coefficient of sliding friction.

Any coasting wheeled vehicle will gradually slow down due to rolling resistance including that of the bearings, but a train car with steel wheels running on steel rails will roll farther than a bus of the same mass with rubber tires running on tarmac. Factors that contribute to rolling resistance are the (amount of) deformation of the wheels, the deformation of the roadbed surface, and movement below the surface. Additional contributing factors include wheel diameter, speed, load on wheel, surface adhesion, sliding, and relative micro-sliding between the surfaces of contact. The losses due to hysteresis also depend strongly on the material properties of the wheel or tire and the surface. For example, a rubber tire will have higher rolling resistance on a paved road than a steel railroad wheel on a steel rail. Also, sand on the ground will give more rolling resistance than concrete.

Usage examples of "rolling resistance".

If the load is carried in a wheeled vehicle, riding on rails, the rolling resistance of the load is perhaps 1/100th to 1/250th of its weight.

Andy, me, Howie, another two local lads and a couple of the traveller boys -down in the snooker room where there's a beat-up looking table and a leak in the ceiling that turns the whole of the stained, green-baize surface into a millimetre-shallow marsh, water dripping from each pocket and dribbling down the bulky legs to the sopping carpet, and we play snooker by the light of the hissing gas lamps, having to hit the white ball really hard even for delicate shots because of the extra rolling resistance the water causes, and the balls make a zizzing, ripping noise as they race across the table and sometimes you can see spray curving up behind them and I'm feeling really drunk and a bit stoned from a couple of strong Js smoked out in the garden earlier with the travellers but I think this dimly lit water-hazard snooker is just hilarious and I'm laughing maniacally at it all and I put an arm round Andy's neck at one point and say, You know I love you, old buddy, and isn't friendship and .