Relation Between Calorie and Joule - A Complete Guide
A calorie and a joule are both units of energy. They help us measure how much heat or work is involved in any physical process. Between the two, a calorie and the joules is that them-they are fundamentally a concept of physics bridging thermal energy-mechanical energy in a sense. While heat is currently measured by calories, joules represent energy across any technically SI standard unit. Their interconversion is the basis of all thermodynamics, energy transfer, and many everyday activities such as nutrition application problems.
This Story also Contains
- What is a Calorie?
- What is Joule?
- What is the Relationship Between Joule and Calorie
- Why is 1 Calorie 4.2 Joules?
- Joule Calorie Conversion
- Joule to Calorie
- Applications of Joule
- Applications of Calorie
Also, read
What is a Calorie?
Calorie is the unit of heat in the C.G.S. system, also called the practical unit of heat while the S.I. unit of heat is the joule. However, the Calorie unit is more widely used when heat is measured. This unit was formulated way before it was recognized that heat is a form of energy.
What is Joule?
Joule is known as the SI unit of work or energy. One Joule is the amount of work done when the force of one Newton acts upon an object in the direction of movement for a distance of one metre.
What is the Relationship Between Joule and Calorie
We can convert calories to joules and vice-versa by a simple conversion relation, i.e. 1 calorie is equal to 4.186 joules.
1 Cal = 4.186 joule = 4.2 joule
We can also use the unit kcal meaning kilocalories. 1 kcal to cal can be converted by a simple conversion relation, i.e. 1kcal=1000cal.
Why is 1 Calorie 4.2 Joules?
1 calorie is defined as the amount of heat required to raise the temperature of 1 gram of water by $1^{\circ} \mathrm{C}$.
But in physics, energy must be measured in the SI unit - the joule (J).
So scientists experimentally measured how much mechanical work (joules) is needed to produce the same heating effect as $\mathbf{1}$ calorie.
Through precise experiments (like Joule's paddle-wheel experiment), they found:
Heating $\mathbf{1 g}$ of water by $\mathbf{1}^{\boldsymbol{\circ}} \mathbf{C}$ requires $\mathbf{4 . 1 8 6}$ joules of energy.
That is why:
1 calorie = 4.186 joules $\approx 4.2$ joules
Joule Calorie Conversion
In physics, the conversion between two units of energy, calorie to joule and joule to a calorie is crucial in solving problems. Scroll down the page for the list of values and their conversion from calorie to joule and joule to calorie.
Calorie to Joule
The table shown below consists of a few of the most popular calorie-to-joule conversion values-
| Calorie | Joule |
| 1 | 4.184 |
| 20 | 83.68 |
| 30 | 125.52 |
| 40 | 167.36 |
| 50 | 209.2 |
| 100 | 418.4 |
| 500 | 2092 |
| 1,000 or 1 kcal | 4184 |
| 5,000 or 5 kcal | 20920 |
| 10,000 or 10 kcal | 41840 |
Joule to Calorie
The table shown below consists of a few of the most popular Joule to Calorie conversion values-
| Joules | Calories |
| 1 | 0.2388 |
| 10 | 2.388 |
| 20 | 4.776 |
| 30 | 7.164 |
| 40 | 9.552 |
| 50 | 11.94 |
| 100 | 23.88 |
| 500 | 119.4 |
| 1000 | 238.8 |
| 5000 | 1194 |
Applications of Joule
1. Work: Work done by a force is measured in joules.
2. Mechanical Energy: Kinetic and potential energies are expressed in joules.
3. Electrical Energy: Energy used by electrical appliances is measured in joules.
4. Heat in SI Unit: Heat produced in machines or resistors is written in joules.
5. Scientific Calculations: All SI-based energy calculations use joules.
Applications of Calorie
1. Heat Measurement: Used to measure heat needed to raise the temperature of substances.
2. Food Energy: Energy value of food is expressed in calories/kilocalories.
3. Body Energy Needs: Daily energy intake and expenditure are calculated in calories.
4. Calorimetry: Heat changes in chemical reactions are measured in calories.
5. Traditional Heat Units: Some older books and instruments still use calories.
Frequently Asked Questions (FAQs)
We cannot round it off to 1 cal= 4 joules because there will be a significant error/ difference/discrepancy in work done (and hence the heat) needed to raise the temperature of 1g of water from 14.5 ̊C to 15. 5 ̊C (as work and heat are equivalent here, i.e. we need 4.186 J of work to be done to heat that amount of water to raise its temperature by one degree).
Kg
1 Cal=4.186 J
80 cal g-1