HOW TO CALCULATE JOULES?
Have you ever found a Joules word when reading the manual for electrical products and wondering what it really is? Have you ever wanted to count Joules but thought it was too difficult?
Joule is an important measurement unit for so much of what we do in the modern world, but most of us don’t know anything about it. Don’t worry, we are here to explain exactly what Joules so you don’t need to be afraid anymore.
In science, Joule is an energy unit or work. There are several ways to calculate Joules. Read how to calculate Joules here.
In this article, we will guide you through how to calculate Joules for the four most common use: energy, electrical energy, kinetic energy, and work.
What is Joule?
Joule is an important measurement unit in the international metric system. The metric system also includes other important measurement units, such as meters, kilometers, seconds, and ampere.
Most important: Joule is an energy unit.
Joule Formulas
There are a number of very useful formulas for working out joules. Here is a quick reference list. We will go through each of them below.
- Joules = watts x seconds
- Joules = amps² x ohms x seconds
- Joules = ½ x mass x (meters/seconds)²
- Joules = newtons x meters
How do you count Joules?
There is no single formula for Joules because energy comes in various forms. For example, it can be expressed as electricity, heat or work.
Instead, there are a number of different ways to calculate Joules, depending on what you use for it. Below, you will find the most common situation where Joules are used.
How to Calculate Energy in Joules
Formula:
- Energy = power x time
- Joules = watts x seconds
This is the most basic formula for Joules. Basically, you can find out how many joules are given by multiplying power with time.
Watt is a power unit. You may have seen it on the light bulb or electrical equipment that you have bought. Joule is an important unit in working on energy efficiency of these items.
This is because one watt is the amount of energy (joules) that is expended by the device each second. So, if you see a device like a lightbulb or washing machine that has a certain number of watts or kilowatts, you will know how much energy that device uses.
To learn more about how much energy your appliances use, you can take a look at this useful tool to convert kW to kJ.
How to Calculate Electrical Energy in Joules
- Electrical energy = current² x resistance x time
- Joules = amps² x ohms x seconds
Electrical energy is actually the same as the joule formula for energy in watts. This is because a watt is equal to (amps² x ohms).
An amp, also called an ampere, is a unit of electrical current. An ohm is a unit of electrical resistance. These units are particularly useful when manufacturing things like circuit boards.
Circuit boards use resistors to moderate the flow of electricity throughout a system. So the amount of energy expended by a circuit board in one second is just the square of the electrical current multiplied by the resistance within the circuit.
You can learn more about how circuits work here.
How to Calculate Kinetic Energy in Joules
Formula:
- Kinetic energy = ½ x mass x velocity²
- Joules = ½ x kilograms x (meters/seconds)²
Kinetic energy is the amount of energy that an object possesses in motion. For example, if you drop a bowling ball off a building, the bowling ball possesses a certain amount of energy.
This is interesting because you can work out the equivalent amount of energy of a falling bowling ball to other types of energy, like a burning lightbulb.
The formula for kinetic energy in joules is pretty straightforward. You need to know the mass of the object, as well as the velocity at which it is traveling.
For example, you could work out the mass of a bowling ball and then drop it off a building to work out what its velocity is. To work out the velocity, you first work out how many meters it travels each second. Once you have that number, you square it, and then you get your velocity.
A bowling ball will accelerate when it is dropped off a building as it gathers momentum. Eventually, though, it will reach terminal velocity. Terminal velocity is just the maximum velocity that a falling object can reach.
Terminal velocity is a little bit complicated. But, as a quick reference, an object reaches terminal velocity when the drag force and buoyancy force of a falling object become equal to the force of gravity. You can learn more about terminal velocity here.
So, all you have to do is work each of those things out, and then you can compare the amount of energy your bedroom light uses and compare it to the amount of energy possessed by a falling bowling ball.
How to Calculate Work in Joules
Formula:
- Work = force x distance
- Joules = newtons x meters
In physics, work is the amount of energy that is expended when a given force is exerted over a given distance. For example, you might want to find the amount of work produced by a weightlifter who lifts a certain amount of weight from the ground to above their head.
To work out the force of an object, you need to know what a newton is. A bit like terminal velocity, a newton is complicated.
Here is a short description: one newton is the amount of force that is used when one kilogram is accelerated at the rate of one meter per second squared.
Now You Have the Joules
Now you know exactly how to calculate joules. More importantly, now you can compare the amount of energy you exert in the gym to the amount of energy exerted by falling bowling balls and burning light bulbs!
For more interesting information and fun tips like this, have a look around our site!
