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Braking distance refers to the distance a vehicle will travel from the point when its brakes are fully applied to when it comes to a complete stop. It is primarily affected by the original speed of the vehicle and the coefficient of friction between the tires and the road surface, [Note 1] and negligibly by the tires' rolling resistance and vehicle's air drag.
The "rolling resistance coefficient" is defined by the following equation: [6] = where is the rolling resistance force (shown as in figure 1), is the dimensionless rolling resistance coefficient or coefficient of rolling friction (CRF), and
A 1000 kg car can depress a 185/65/15 tire more than a 215/45/15 tire longitudinally thus having better linear grip and better braking distance not to mention better aquaplaning performance, while the wider tires have better (dry) cornering resistance. The contemporary chemical make-up of tires is dependent of the ambient and road temperatures.
Generally the force of rolling resistance is less than that associated with kinetic friction. [74] Typical values for the coefficient of rolling resistance are 0.001. [75] One of the most common examples of rolling resistance is the movement of motor vehicle tires on a road, a process which generates heat and sound as by-products. [76]
Unlike other resistive forces, drag force depends on velocity. [2] [3] Drag force is proportional to the relative velocity for low-speed flow and is proportional to the velocity squared for high-speed flow. This distinction between low and high-speed flow is measured by the Reynolds number.
Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current.
The COR is a property of a pair of objects in a collision, not a single object. If a given object collides with two different objects, each collision has its own COR. When a single object is described as having a given coefficient of restitution, as if it were an intrinsic property without reference to a second object, some assumptions have been made – for example that the collision is with ...
Traction between two surfaces depends on several factors: Material composition of each surface. Macroscopic and microscopic shape (texture; macrotexture and microtexture) Normal force pressing contact surfaces together. Contaminants at the material boundary including lubricants and adhesives.