Respuesta :
A light-rail commuter train accelerates at a rate of 1.40 m/s2, it take 15.17s to reach its top speed of 76.5 km/h, starting from rest.
What is the difference between speed and velocity?
When describing the motion of the objects in terms of distance, time, and direction, physicists use the basic quantities of speed and velocity. Two terms and two distinct meanings. Yet, not uncommonly, we hear these terms used in interchangeably. So, what is the difference? Why is it incorrect to use terms speed and velocity interchangeably?
The reason is very simple. Speed is time rate at which an object is moving along a path, while velocity is the rate and direction of an object’s movement. Put another way, the speed is a scalar value, while velocity is a vector.
The mathematical calculation for speed is relatively straightforward, wherein the average speed of an object is calculated by dividing the distance traveled by the time it took the object to travel distance. Velocity, on the other hand, is more complicated mathematically and can be calculated in different ways, depending on what information is available about object’s motion. In its simplest form, average velocity is calculated by dividing change in position (Δr) by change in the time (Δt).
The formula to find the acceleration is:
[tex]a=\frac{v-u}{t}[/tex]
[tex]t=\frac{v-u}{a}[/tex]
[tex]=\frac{(21.25-0)}{1.40}[/tex]
[tex]=15.17s[/tex]
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