Horsepower is a unit of measurement of power. The term was originally coined by a Scottish engineer to compare the power of the steam engine to that of horsepower. This article tells you how to calculate the horsepower of a vehicle's engine, an electric motor, and even your body.
Steps
Part 1 of 3: Calculate the Horsepower of the Car
Step 1. Find your car's torque values
Consult the vehicle manual and look for the mechanical moment value in the "technical specifications" section or on the index page. If you don't have the manual, you can search online. For example, you can type in the search bar the word "couple" followed by the manufacturer, the model and the year of production of the machine; this way you should find the values that interest you.
Step 2. Obtain the rotational speed of the motor
This data is also readily available in the manual. You can search online if you don't have the manual or the value is not indicated. Enter the model, the year of production and the manufacturer of your car followed by the words "engine rotation speed", you will certainly find the information you need.
Step 3. Multiply the torque value by the rotational speed value
At this point you have to use the formula (RPM * T) / 5.252 = HP, where RPM represents the rotation speed expressed in revolutions per minute, T is the torque and 5.252 are the radians per second. The first calculation you need to perform is the multiplication between the mechanical moment and the rotation speed.
For example, a Porsche generates 480 Nm of torque at 2500 rpm. If we carry out the calculations indicated in the equation, we obtain that: (2,500 * 480) is equal to 1,200,000
Step 4. Now divide your product by 5.252
The quotient indicates the horsepower of the machine. If we still consider the example of the Porsche, we get that 1,200,000 / 5,252 = 228, 48, so we can say that the car has 228 horsepower.
Part 2 of 3: Calculating the Horsepower of an Electric Motor
Step 1. Find the current (I), efficiency (Eff) and potential difference (V) of the motor
The potential difference will be expressed in volts, the current intensity in amperes and the efficiency is a percentage value. This data should be reported directly on the engine.
Step 2. Using the formula (V * I * Eff) / 746 = HP, you can determine the horsepower of the electric motor
Multiply between them the potential difference, the current intensity and the efficiency, finally divide the product by 746. Consider, for example, a motor with 230 v driven by a current intensity of 4 amperes that reaches an efficiency of 82%. In this case we can say that it has 1 horsepower.
Convert the yield value to a decimal number before proceeding with the calculations. For example, the 82% yield is 0.82
Part 3 of 3: Calculate a Person's Horsepower
Step 1. Weigh yourself
Find your weight in kilograms and write down the value. If your scale is calibrated in pounds, you can convert the data into kilograms by multiplying it by 0.453.
Step 2. Find an obstacle-free stairway
You have to run up the stairs while you time yourself, so you have to avoid them being too busy.
Step 3. Measure the total height of the staircase
First, measure the height of a step in meters. Then it counts how many steps make up the scale and multiplies the two values together. At this point you have the total height and you need to write it down.
If your ruler is calibrated in inches, you can convert this by multiplying it by 0.0254m
Step 4. Time the time it takes you to walk all the way up the stairs
Take a short run and when your foot touches the first step, start the stopwatch. When both feet land on the last step, stop the clock. Also note the time taken in seconds. Remember that there are 60 seconds in every minute.
Step 5. Use the formula (m * 9, 81 * h) / t = P to calculate your power
In this example "m" indicates your weight, "h" the height of the stairs, 9, 81 is the acceleration of gravity which is constant and must be considered; finally "t" is the time taken to climb the staircase expressed in seconds. The final result is your power expressed in watts.
For example, if you weigh 90 kg and walked a 4-meter-high staircase in 4 seconds, then your wattage power is [(90 * 9, 81 * 4)] / 4 = 882.9 watts
Step 6. Calculate the horsepower
Divide the power in watts by 735.5 to get the value in HP. Generally the result is equal to 1-2 horsepower.
Advice
- Use the calculator to perform multiplications and divisions.
- Always double-check your calculations to make sure you have typed the numbers correctly on the calculator.
