Instantaneous Velocity graph problem

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Homework Help Overview

The discussion revolves around finding the instantaneous velocity at a specific time (1 second) based on a given coordinate point (1, 4) on a position vs. time graph. The subject area is kinematics, focusing on the concept of velocity as it relates to graphical representation of motion.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss methods for finding instantaneous velocity, including differentiation and drawing a tangent line to the graph. Questions arise regarding the completeness of the provided information, particularly the need for a full position function or additional data points to accurately determine the velocity.

Discussion Status

The discussion is active, with participants exploring different methods to approach the problem. There is an emphasis on the necessity of more information to accurately calculate instantaneous velocity, and some guidance has been offered regarding the interpretation of the graph and the definition of velocity.

Contextual Notes

Participants note the lack of a complete position function and question the adequacy of the single coordinate point provided for determining instantaneous velocity.

iiskenny
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Find the instantaneous velocity at 1 s.
Answer in units of m/s.

the coordinate for 1s is (1,4)

How do i find the instantaneous velocity?
 
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welcome to pf!

hi iiskenny! welcome to pf! :smile:
iiskenny said:
Find the instantaneous velocity at 1 s.
Answer in units of m/s.

the coordinate for 1s is (1,4)

How do i find the instantaneous velocity?

by differentiating, or by drawing a tangent to the graph …

but what's the rest of this function? :confused:
 
Velocity is defined as the rate of change of position divided by the rate of change of time.

This is the same as saying that velocity is the slope of the position vs. time graph.

Therefore, instantaneous velocity at 1s is the slope of the position vs. time graph at t=1s.
 
But, as both tiny-tim and Beaker87 have said, just knowing the position is not enough! That's like saying "at 2:00, a car was at 4th st and Central ave. How fast was it going?"!

You need to know something about it motion through that point. An actual "position function", telling where it was at different times, would be excellent- take the derivative of the function. If you are given a "x versus t" graph, you can estimate the slope of the tangent line at the given point. If you are given a position at another time, before or after this t= 1 you can estimate the speed at t= 1. If you are given the position at times before and after as well as at t= 1, you can get a better estimate.

Now, what information are you really given? What is the full statement of the question?
 

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