# Calculating Horsepower/Torque from Acceleration/Mass

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 dont 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

Hootenanny
Staff Emeritus
Gold Member
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:
Hootenanny
Staff Emeritus