Calculating Horsepower/Torque from Acceleration/Mass

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Homework Help Overview

The discussion revolves around calculating horsepower and torque from acceleration and mass, specifically using kinetic energy formulas and conversion methods. The original poster presents a scenario involving a vehicle with a constant mass and provides sample data for speed and time intervals.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate kinetic energy using the formula KE = (1/2)(m)(v^2) and subsequently convert this energy into horsepower. Participants question the completeness of the provided data and the relevance of certain variables, such as RPM.

Discussion Status

The discussion is ongoing, with the original poster seeking clarification on potential errors in their calculations. Some participants have requested more information about the problem setup, indicating that the conversation is exploring the adequacy of the data provided.

Contextual Notes

The original poster mentions having limited data, specifically the vehicle weight and time-sampled speed data, which may impact the calculations and interpretations being discussed.

Sentient
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Apologies in advance if this is not the correct forum.

This is (what seems to me) an old question people have been playing with for a while, but I don't seem to be able to figure out where I have gone wrong.

Could someone point out the mistake in my math from the following example:

Constant Mass = 1180Kg

Sample 1 @ 2 secs
Kilometers/Hour = 37
Meters/Sec = 10.278
RPM = 3000

Sample 2 @ 3 secs
Kilometers/Hour = 46
Meters/Sec = 12.778
RPM = 3780

Sample 3 @ 4 secs
Kilometers/Hour = 59
Meters/Sec = 16.389
RPM = 4860


Using the formula: KE = (1/2)(m)(v^2) I calculated

KE1 = 0.5 * 1180 * (10.278 * 10.278) = 62326 ??Joules??
KE2 = 0.5 * 1180 * (12.778 * 12.778) = 96333.6 ??Joules??
KE3 = 0.5 * 1180 * (16.389 * 16.389) = 158473.6 ??Joules??

Using the formula: W = (KE / Time) given the sampling time is 1sec
W = KE.

Converting (roughly) from W (watts) to HP: HP = W / 746

HP1 = 83.54
HP2 = 129.12
HP3 = 212.32

I know from another piece of software that the correct values should be:

HP1 = 59
HP2 = 76
HP3 = 105


Could someone be kind enough to point out my fault. Greatly appreciated.

Tony
 
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Could you start by stating the question exactly as it is given please.

~H
 
The question is:

Plot a graph showing horsepower at given time intervals based on sampled data.There are actually 10 samples, but I have only included 3 for simplicity. The original data only included Time, Kilometers/Hour and RPM (although I don't think RPM is needed for this part of the question). I converted KPH to meters/sec as I think this is the correct unit for KE.
 
Last edited:
And you have no other information regarding the vehical?

~H
 
I was given the vehicle weight of 1180kg, and the time-sampled data, but nothing else.
 

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