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The other component is the reaction distance, which is the product of the speed and the perception-reaction time of the driver/rider. A perception-reaction time of 1.5 seconds, [ 2 ] [ 3 ] [ 4 ] and a coefficient of kinetic friction of 0.7 are standard for the purpose of determining a bare baseline for accident reconstruction and judicial ...
The two-second rule is useful as it can be applied to any speed. Drivers can find it difficult to estimate the correct distance from the car in front, let alone remember the stopping distances that are required for a given speed, or to compute the equation on the fly (for example, braking distance is roughly calculated as b = s 2 /20, where b is the braking distance in metres and s is car ...
The first HDD [11] had an average seek time of about 600 ms. [12] and by the middle 1970s, HDDs were available with seek times of about 25 ms. [13]Some early PC drives used a stepper motor to move the heads, and as a result had seek times as slow as 80–120 ms, but this was quickly improved by voice coil type actuation in the 1980s, reducing seek times to around 20 ms.
Gear inches is an imperial measure corresponding to the diameter in inches of the drive wheel of a penny-farthing bicycle with equivalent ( direct-drive) gearing. A commonly used metric alternative is known as metres of development or rollout distance, which specifies how many metres a bicycle travels per revolution of the crank.
Headway. Headway is the distance or duration between vehicles in a transit system measured in space or time. The minimum headway is the shortest such distance or time achievable by a system without a reduction in the speed of vehicles. The precise definition varies depending on the application, but it is most commonly measured as the distance ...
Tangential speed is the speed of an object undergoing circular motion, i.e., moving along a circular path. [ 1] A point on the outside edge of a merry-go-round or turntable travels a greater distance in one complete rotation than a point nearer the center. Travelling a greater distance in the same time means a greater speed, and so linear speed ...
Comoving distance and proper distance. Comoving distance is the distance between two points measured along a path defined at the present cosmological time. For objects moving with the Hubble flow, it is deemed to remain constant in time. The comoving distance from an observer to a distant object (e.g. galaxy) can be computed by the following ...
Time dilation. Time dilation is the difference in elapsed time as measured by two clocks, either because of a relative velocity between them ( special relativity ), or a difference in gravitational potential between their locations ( general relativity ). When unspecified, "time dilation" usually refers to the effect due to velocity.