Power (Physics) Calculator Formula

Understand the math behind the power (physics) calculator. Each variable explained with a worked example.

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Formulas Used

Power

power = work / time

Power (kW)

power_kw = work / time / 1000

Power (hp)

power_hp = work / time / 745.7

Variables

VariableDescriptionDefault
workWork Done(J)1000
timeTime(s)5

How It Works

Mechanical Power

Power is the rate at which work is performed or energy is transferred.

Formula

P = W / t

One watt equals one joule per second. To convert watts to horsepower, divide by 745.7.

Worked Example

A motor does 1000 J of work in 5 seconds.

work = 1000time = 5
  1. 01P = W / t
  2. 02P = 1000 / 5
  3. 03P = 200 W
  4. 04P = 0.2 kW
  5. 05P = 200 / 745.7 = 0.268 hp

Frequently Asked Questions

What is the difference between power and energy?

Energy is the total amount of work done, while power is the rate at which that work is done. A 100 W bulb uses 100 joules of energy every second.

How do you convert watts to horsepower?

Divide watts by 745.7 to get mechanical horsepower. For example, 746 W is approximately 1 hp.

What is a kilowatt-hour?

A kilowatt-hour (kWh) is a unit of energy equal to 1000 watts sustained for one hour, or 3,600,000 joules.

Learn More

Guide

How to Calculate Force and Work

Learn how to calculate force (F = ma) and work (W = Fd) step by step. Covers net force, work-energy theorem, power, and real-world applications with clear examples.

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