If you know the displacements of a moving object between two points along its path, and you know the time it took for the object to get from one point to another, can you determine the object’s instantaneous velocity and average velocity? Explain. Thank you!!!
Velocity is a physical property of a moving object. Unlike speed it also includes the direction in which the object is moving. An object moving with 2 km/hr speed towards your right and another with 2km/hr speed towards your left possess different velocities. Since the terms left and right are relative one should go with a more apt co ordinate system to express velocity. To explain, in our naive naive way with lefts and right, Mike might observe a ball with velocity 2km/hr towards his ‘right’. But Clive facing him, might see the same thing with velocity 2km/hr towards his ‘left’. Both velocities are same!
Term instantaneous velocity refers to the velocity at a particular instant. This is a useful concept as most objects in everyday cases change their velocity from time to time, either changing their speed(magnitude) or direction of motion. Average velocity is the time averaged velocity of an object over an interval of time. It is simply the sum of product of it’s velocity and time for which it travelled with that velocity over the total interval of time divided by the total time. It simply turns out to be the displacement divided by time. But instantaneous velocity has to do with the speed and direction of motion at a particular instant of time.
You can always sped up a bit, slow down, turn around or do all sorts of jiggly motions before arriving at the same points within the same time gap. So displacement alone is not sufficient to know instantaneous velocity. Another way to think about it is, to analyze the information you have. You have a time interval, say 0 to T. and two positions, A and Z. The object moves from position A at time 0 to position Z at time T.
For an in between position, say P at time Tp there is no way you can construct a synthesis to determine it’s velocity(instantaneous). A right synthesis should discriminate between a choice of speeding up at P or slowing down at P, that is information which is not at hand. But the final result or the average value of displacement is all you have. So you can know the average velocity, not instantaneous velocity.