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Electrical science and principles
Published in Trevor Linsley, Electrical Installation Work Level 2, 2019
In everyday conversation we often use the word velocity to mean the same as speed, and indeed the units are the same. However, for scientific purposes this is not acceptable since velocity is also concerned with direction. Velocity is speed in a given direction. For example, the speed of an aircraft might be 200 miles/h, but its velocity would be 200 miles/h in, say, a westerly direction. Speed is a scalar quantity, while velocity is a vector quantity. Velocity=Distance(m)Time(s)
Straight-level flight
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
The specific speeds in straight-line level flight include maximum speed, cruising speed, minimum drag speed, maximum range speed, speed for absolute ceiling, and maximum endurance speed. It is emphasized again that these topics are discussed for jet aircraft, and in the next chapter, they are reintroduced for prop aircraft. In this chapter, several statistical tables have been prepared to illustrate the real data of current aircraft performance specifications. They provide the reader with a feeling of how a given aircraft is performing. For the purpose of simplicity, we sometimes use “cruising flight” instead of “straight-line level flight”. Although, velocity is a “vector” quantity and speed is a “scalar” value, in this book, we use both velocity and speed interchangeably, but we mean a vector quantity in both cases. In majority of the cases, when we use the term “speed” or “velocity”, in fact we mean aircraft speed or “airspeed”.
Using trenchless technology to save costs associated with traffic delays
Published in Mark Knight, Neil Thomson, Underground Infrastructure Research, 2020
S.L. Tighe, T. Lee, R.C.G. Haas
The three basic variables associated with traffic capacity analysis are volume or the rate of flow, speed and density. The volume is simply the number of vehicles that pass over a given point or section during a given interval. The rate of flow is an equivalent hourly rate at which vehicles pass over a given point during a given amount of time. This amount of time is usually defined as fifteen minutes. Speed is the rate of motion expressed as distance per unit time. This is an important measure of the quality of traffic service provided for the motorist. The third variable, density is also important in traffic analysis as it measures the number of vehicles which occupy a given length of a lane or roadway at a particular instant [TRB 94].
Water transit and excess travel: discrete choice modelling of bus and ferry trips in Brisbane, Australia
Published in Transportation Planning and Technology, 2019
Michael Tanko, Matthew I. Burke, Barbara Yen
A number of variables were derived from the existing data. Firstly, travel time was calculated from the difference in alighting and boarding time stamps. Distance of journey was derived by measuring the route shapefile length of each origin-destination pairing of stops to and from the city. For the selected stops there are two separate bus route numbers (300 and 305) that follow the same route but only differ in the stops that they make. Boardings and alightings also occur at different stops depending on whether they are inbound or outbound trips. The same was done with ferry trips, where three different trip lengths are possible depending on boardings or alighting at North Quay (the longest), QUT (the middle) and Riverside (the shortest trip). Average speed was then calculated by distance divided by travel time. Finally, two dummy variables were created to indicate AM and PM peak trips. It should be noted that travel fare/cost is not a relevant variable in this context, as bus and ferry journeys have equal fares. Tables 1–3 show the descriptive statistics of the variables used in the study, including minimum, maximum, mean, standard deviation, skewness, and kurtosis values for each bus trips, ferry trips and the totals of all separate bus and ferry trips.
On the use of history of mathematics: an introduction to Galileo's study of free fall motion
Published in International Journal of Mathematical Education in Science and Technology, 2018
Juan Carlos Ponce Campuzano, Kelly E. Matthews, Peter Adams
On the other hand, notwithstanding the fact that students had previous mathematical training and studied motion formally in first courses of calculus or physics; we predicted that it was not an easy task for them to answer Question 2. Consistent with this, students’ answers also demonstrated how their mathematical thinking was challenged, as evident in the following responses: Defining speed without an elapsed time is incredibly hard. The term instantaneous implies a still, snapshot of all time, and doing so removes all frames of reference, or gives every object the same one. This means that everything looks like it is standing still; in such a world every object has zero velocity, or perhaps, velocity cannot even exist. In order to define an instantaneous speed, differential calculus must be used.I do not believe you can refer to instantaneous speed without an elapsed time period since speed is defined as a function of time. I see instantaneous speed as the speed over an infinitesimally small period of time, so small that it is nearly impossible to define the separation from one unit of this time to another.Students’ answers were classified into three categories: responses referred to (1) the rate of change, (2) a time period, and (3) an infinitesimal period of time. Seven students (approximately 9% of the total) expressed that they did not know, or were not sure, how to answer this question.
Factors affecting bike-sharing system demand by inferred trip purpose: Integration of clustering of travel patterns and geospatial data analysis
Published in International Journal of Sustainable Transportation, 2022
Meesung Lee, Sungjoo Hwang, Yunmi Park, Byungjoo Choi
Figure 4 shows details of the travel patterns from the BSS trip data, including travel duration, average speed, travel distance, the shortest distance, and roaming distance. Here, the shortest distance is the minimum distance between the rental station and the return station, which was obtained using the two stations’ latitudes and longitudes. The roaming distance was measured as the difference between the actual travel distance and the shortest distance. For example, if a user travels 15 km and returns the bike to another station 5 km away from the rental station, the shortest distance is 5 km, and the roaming distance is 10 km. The average speed was calculated by dividing the travel distance by the travel duration.