Calculating Horsepower/Torque from Acceleration/Mass

  • Thread starter Sentient
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I am trying to calculate the horsepower at each time interval using the kinetic energy formula. In summary, the conversation is about a question regarding plotting a graph showing horsepower at given time intervals based on sampled data. The person has been trying to figure out where they went wrong in their calculations using the kinetic energy formula, given the vehicle weight and time-sampled data. They also mention converting from Kilometers/Hour to meters/sec and then to horsepower. They are seeking assistance in finding their mistake.
  • #1
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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  • #2
Could you start by stating the question exactly as it is given please.

~H
 
  • #3
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:
  • #4
And you have no other information regarding the vehical?

~H
 
  • #5
I was given the vehicle weight of 1180kg, and the time-sampled data, but nothing else.
 

What is horsepower and torque?

Horsepower is a unit of power that measures the rate at which work is done, while torque is a measure of rotational force. Horsepower is typically used to measure the power of engines, while torque is used to measure the twisting force produced by an engine.

How do you calculate horsepower from acceleration?

To calculate horsepower from acceleration, you will need to know the mass of the object and the acceleration it experiences. The formula for calculating horsepower from acceleration is: horsepower = (mass x acceleration) / 550. This formula assumes that the object is moving in a straight line and the units for mass are in pounds and acceleration is in feet per second squared.

Is there a way to calculate torque from mass and acceleration?

Yes, torque can be calculated from mass and acceleration. The formula for calculating torque is: torque = (mass x acceleration x radius)/ 32.2. This formula assumes that the object is moving in a circular motion and the units for mass are in pounds, acceleration is in feet per second squared, and radius is in feet.

What is the relationship between horsepower and torque?

Horsepower and torque are related to each other through the formula: horsepower = (torque x RPM)/ 5252. This means that as torque increases, horsepower also increases. However, the relationship between the two is not linear, as horsepower takes into account the rate at which work is done (RPM) in addition to the amount of force (torque) being produced.

Are there any other factors that can affect horsepower and torque?

Yes, there are many other factors that can affect horsepower and torque. Some of these factors include the design and efficiency of the engine, air temperature and pressure, fuel type and quality, and mechanical losses. Additionally, external factors such as air resistance and road conditions can also impact the performance of an engine and affect the calculated horsepower and torque values.

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