Why can't we apply the speed equation in a free fall?

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Discussion Overview

The discussion revolves around the application of the speed equation, Speed = D/T, in the context of free fall, where acceleration due to gravity is constant at 9.8 m/s². Participants explore the implications of changing velocity during free fall and the distinction between average speed and instantaneous speed.

Discussion Character

  • Debate/contested, Conceptual clarification, Technical explanation

Main Points Raised

  • Some participants note that in free fall, acceleration is constant, leading to an increase in speed/velocity over time.
  • One participant questions the applicability of the Speed = D/T formula when velocity is changing, suggesting that a single speed may not be representative.
  • Another participant asserts that the Speed = D/T formula can be used to calculate average speed, clarifying that this represents the average of all velocities during the fall.
  • It is mentioned that to find the velocity at a specific moment, kinematic equations should be employed instead of the average speed formula.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of the Speed = D/T formula in free fall, with some supporting its use for average speed and others emphasizing the limitations due to changing velocity. The discussion remains unresolved regarding the best approach to describe speed in this context.

Contextual Notes

The discussion highlights the distinction between average speed and instantaneous speed, as well as the need for kinematic equations to determine velocity at specific points in time. There is an implicit assumption that participants understand the concepts of average and instantaneous speed.

axer
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Hello, so i know in a free fall the acceleration is constant (9.8 m/s2) therefore speed/velocity is increasing.. But I am wondering why we can't use Speed=D/T
 
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Go back and think about the several points you just made. If velocity is changing, does a formula that gives a single speed over time make sense to you.
 
axer said:
Hello, so i know in a free fall the acceleration is constant (9.8 m/s2) therefore speed/velocity is increasing.. But I am wondering why we can't use Speed=D/T

You can and that will give you the average speed.
 
axer said:
Hello, so i know in a free fall the acceleration is constant (9.8 m/s2) therefore speed/velocity is increasing.. But I am wondering why we can't use Speed=D/T
You most definitely can use the velocity = d/t formula. Just keep in mind that the speed you will find from this equation will be the average velocity, this means that it is the average of all the velocities combined since you are combining the total distance and total time.

If you want to find the velocity at any given point in time or space, then you need to use the kinematic equations.
 

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