Finding Velocity on a Position/Time Graph

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SUMMARY

The discussion focuses on calculating velocity from a position/time graph, specifically addressing the confusion surrounding the formula used. The correct formula for velocity is derived from the displacement divided by the time interval, rather than the change in velocity over time, which results in acceleration. The accurate calculation for velocity on a straight line graph yields a consistent value of 1.4 m/s North. Miscalculations arise from incorrect application of the slope formula, leading to varying results.

PREREQUISITES
  • Understanding of basic kinematics
  • Familiarity with position/time graphs
  • Knowledge of the slope calculation
  • Proficiency in using the formula for velocity: V = Δx/Δt
NEXT STEPS
  • Study the concept of slope in linear graphs
  • Learn about displacement and its relation to velocity
  • Explore kinematic equations for uniform motion
  • Practice calculating velocity using various position/time graphs
USEFUL FOR

Students in physics, educators teaching kinematics, and anyone seeking to understand the relationship between position and velocity on graphs.

5pirit
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Hey everyone, I'm having trouble finding velocity on a straight line position/time graph. Every single equation I do ends up with a different answer, which doesn't make sense because it's a straight line.

I know the equation is

Vf-Vi/Tf-ti

The answer to this question is 1.4m/s N

Example:

45-25/28-16= 1.666666m/s Wrong answer. I'm just taking these from the graph by the way.

25-20/16-14= 2.5, completely different answer.

Could someone please explain what I'm doing wrong? I'm calculating the slope which seems to change with every calculation that I do, which I understand is wrong.
 
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Try to post the graph so we can see it. Also, if your v is velocity, you are dividing a velocity change by an elapsed time. That gives acceleration. If you want velocity, divide displacement by time.
 
5pirit said:
Hey everyone, I'm having trouble finding velocity on a straight line position/time graph. Every single equation I do ends up with a different answer, which doesn't make sense because it's a straight line.

I know the equation is

Vf-Vi/Tf-ti

The answer to this question is 1.4m/s N

Example:

45-25/28-16= 1.666666m/s Wrong answer. I'm just taking these from the graph by the way.

25-20/16-14= 2.5, completely different answer.

Could someone please explain what I'm doing wrong? I'm calculating the slope which seems to change with every calculation that I do, which I understand is wrong.
Hello 5pirit. Welcome to PF !

What is the slope of that line?
 

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