How Do You Convert Acceleration from m/s^2 to km/h^2?

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Homework Help Overview

The discussion revolves around converting acceleration from m/s² to km/h² in the context of an airplane's motion. The original poster presents a scenario where an airplane accelerates from rest at a constant rate and seeks to determine its final velocity in km/h after a specified time interval.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss whether to convert acceleration before using it in kinematic equations and explore different methods to find the final velocity. There are questions about the appropriateness of using various kinematic equations given the provided parameters.

Discussion Status

Some participants suggest straightforward approaches, such as calculating final velocity in m/s before converting to km/h. Others express uncertainty about the correctness of their calculations and the necessity of unit conversions, indicating a mix of interpretations and methods being considered.

Contextual Notes

There is mention of using different kinematic equations based on the available data (acceleration and time versus distance). Participants also reflect on the implications of their calculated speeds in a real-world context, questioning the validity of their results.

Henrybar
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An airplane starts from rest and accelerates at a constant rate of 3.00 m/s^2 for 30.0s before leaving the ground. What is the airplanes velocity in km/h at the end of this interval?

Vi=0m/s
Vf=?
a=3m/s^2
Δt=30s


Not sure if I did it right or if I am also supposed to convert the acceleration to km/h before plugging into equation. If so, how do i convert 3m/s^2 to km/h^2?? Please help
 
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Just get the final velocity in m/s then convert to km/h. That would be the simplest thing to do.
 
Henrybar said:
An airplane starts from rest and accelerates at a constant rate of 3.00 m/s^2 for 30.0s before leaving the ground. What is the airplanes velocity in km/h at the end of this interval?

Vi=0m/s
Vf=?
a=3m/s^2
Δd=1350m
= 1.35km

Vf^2=Vi^2 + 2aΔd
Vf=2.84km/h

Not sure if I did it right or if I am also supposed to convert the acceleration to km/h before plugging into equation. If so, how do i convert 3m/s^2 to km/h^2?? Please help

You are given acceleration and time, not acceleration and distance. You need to use a different version of the kinematic equation -- one that relates velocity to acceleration and time...

And to do any units conversion, just multiply by "one". So if I wanted to convert inches to mm, for example, I'd multiply by 1 = (25.4mm/1 inch), cancel the "inch" units on the top and bottom of the fraction, and be left with the distance in mm. :smile:
 
Henrybar said:
Vf=2.84km/h

Not sure if I did it right

Check your answer using common sense. At that speed, if you were late for the check-in, you would be able to walk down the runway (not even run) and catch up the plane to get on the flight :smile:

Also, it's not "wrong" to find the distance and then the speed (if you do it right), but why not use the formula Vf = Vi + at?
 

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