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Unformatted text preview: CE 3102 Fall 2008 Thought Problem 16 Off Road In traffic accident reconstruction, we often have to estimate or infer the values of unmeasured quantities, such as a vehicle’s initial speed, from quantities we can measure, such as the length of a radius of its yawing path on the pavement. The simplest approach to this is obtained by equating the frictional force available between a vehicle’s tire and the pavement, with the centripetal force needed to cause it to follow a circular path. The leads to the “critical speed formula” xg v r 2 = where r = radius of the vehicle’s path v = initial speed g = gravitational acceleration x= tire/pavement friction coefficient Given a measurement of the path radius, and knowledge of the friction coefficient, an estimate of the vehicle’s speed at the start of the curved path is rxg v ≈ One problem that often arises is that it is difficult to determine an exact value for the tire/pavement friction coefficient. Uncertainty concerning this value will then lead to uncertainty concerning the speed estimate. coefficient....
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- Spring '11
- 2.2 ft, 32.2 ft, 117.0 ft, 532 feet