How Is the Pascal Used for Measuring Energy?
The pascal is symbolized as Pa. It is the SI-derived unit of pressure that is used to quantify internal pressure, stress, Young's modulus, and tensile strength. The unit Pascal is named after the French mathematician, physicist, religious philosopher, and master of prose Blaise Pascal.
In the CGS System, Pascal is defined as one newton per square meter and it is equivalent to 10 baryes (Ba).
In this article, we will learn about the Pascal unit of energy measurement, unit of energy measurement, and unit of measurement of energy in detail.
What is Energy?
The word ‘Energy’ is derived from the Latin word Energeia and the Greek word Ενεργεια. It is a measure of the ability to do mechanical work.
Energy is a fundamental concept relating to the ability to act.
In physics, it is a quantity that every physical system possesses; this quantity is not absolute; however, relative to a state of the system, also known as its reference state or reference level.
The energy of a physical system is the amount of mechanical work that the system can generate if it changes its state to its reference state; for example, if two liters of water cool to 0°C or if a car hits a stone and decelerates from 120 km/h to 0 km/h.
Now, let us understand the energy and its types:
Types of Energy
Energy can be in several forms:
Mechanical Potential - A mechanical potential energy is a possible physical interaction with other objects (for example, gravitational potential energy, mechanical energy).
Kinetic Potential - This energy is contained in macroscopic motion; such as the motion of a car, a ball, and so on.
Chemical - A potential stored in chemical bonds between atoms and molecules.
Electrical - Am electrical potential due to charge interactions
Thermal - The energy contained in the kinetic energy of individual molecules
Nuclear Energy - Potential stored between components of the atomic nucleus. Light can be viewed as energy in the form of photons/waves, depending on the context.
The theory of general relativity (given by Einstein) provides a framework for visualizing mass itself as an expression of energy.
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Unit of Energy Measurement
The official unit of energy measurement is Joule (J). It is the most common unit for measuring energy. In electrical terms, the unit of energy measurement is kilowatt/hour or kWh, used especially for electric energy. The other units MegaJoule, Watt-hour, etc.
Do You Know?
The unit Kilowatt Per Hour unit of energy measurement is used to calculate electricity bills.
Units of Measurement of Energy
As we know that energy is the ability to do work, i.e. energy produces work. According to the second law of thermodynamics, whenever the work is done by absorbing the energy viz: heat from the reservoir, some heat is always rejected to the sink (surrounding). Work and heat are the forms of energy; thus the units of measurement of energy, work, and heat are the same.
Numerous energy measurement systems exist at present but the most commonly used system is the International Systems or SI. Below are the units of measurement of energy, work, and heat in various systems:
1. MKS system (Metric system):
MKS unit is the most commonly used unit to indicate the energy content of the fuel and food, the heat-storing capacity in a reservoir, the capacity of refrigeration, and air-conditioning system, etc.
2. Calories or Cal:
One calorie is the amount of heat required to raise the temperature of 1 gram of water by one degree Celsius. Calorie is a very small unit and the larger unit of the same is Kilocalories or Kcal. Kcal is also more commonly used unit. 1Kcal = 1000 cal.
3. SI unit System:
Joule: The SI system is also the most commonly used unit. Joule unit has been named in honour of the physicist James Prescott Joule (1818–1889). Joule who has made very important contributions in the field of thermodynamics, especially in work and energy.
Joule is a derived unit that is defined as the work done, or energy required to exert a force of one newton on the object for a distance of one meter, so the same quantity may be referred to as a newton meter or newton-meter or simply N.m/N-m.
Even Joule is a small unit; hence, for large units, kilo Joule or KJ is used commonly. 1KJ = 1000J.
4. British Thermal unit:
Btu: One Btu is the energy required to raise the temperature of one pound of water by one degree Fahrenheit.
FAQs on Understanding the Pascal as a Unit of Energy in Physics
1. What is a Pascal (Pa) and what physical quantity does it measure?
The Pascal (Pa) is the SI derived unit of pressure. It is also used to measure other related quantities like internal stress, Young's modulus, and tensile strength. One Pascal is defined as the pressure resulting from a force of one Newton applied perpendicularly to a surface of one square metre (1 N/m²).
2. Is the Pascal a unit of energy?
No, the Pascal is not a unit of energy. It is a unit of pressure. This is a common point of confusion. The correct SI unit for energy, work, and heat is the Joule (J). While Blaise Pascal was a renowned physicist, the unit named after him specifically relates to pressure.
3. What is the formula used to calculate pressure in Pascals?
The formula to calculate pressure (P) in Pascals is: P = F / A. Where:
- P is the pressure in Pascals (Pa).
- F is the perpendicular force applied in Newtons (N).
- A is the area over which the force is distributed in square metres (m²).
4. How is the Pascal unit expressed in terms of fundamental SI units?
The Pascal (Pa) is a derived unit. Since it is defined as one Newton per square metre (N/m²), and a Newton is defined as kg⋅m/s², the Pascal can be broken down into fundamental SI units as kg·m⁻¹·s⁻². This shows its relationship to mass, length, and time.
5. What are some common examples of where the Pascal unit is used?
The Pascal and its multiples are used in many scientific and real-world applications. For example:
- Weather Forecasting: Atmospheric pressure is often reported in hectopascals (hPa).
- Material Science: The strength of materials (tensile strength) is measured in megapascals (MPa) or gigapascals (GPa).
- Engineering: Tyre pressure is commonly measured in kilopascals (kPa).
- Fluid Dynamics: It is fundamental to calculations involving hydraulic systems based on Pascal's Law.
6. How does Pascal's Law relate to the Pascal unit?
Pascal's Law explains the principle behind how pressure is transmitted in a fluid, while the Pascal unit is used to quantify that pressure. The law states that a pressure change at any point in a confined, incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. This is the principle behind hydraulic systems like car brakes and hydraulic lifts, where the pressure at every point is measured in Pascals (Pa).
7. Why is it important to distinguish between pressure (in Pascals) and force (in Newtons)?
Distinguishing between pressure and force is crucial for understanding how effects are distributed. Force (N) is the total push or pull on an object. Pressure (Pa) describes how concentrated that force is over a certain area. For example, a sharp knife cuts effectively not because of a large force, but because the small force is concentrated onto a tiny area, creating very high pressure.
8. What is the difference between 1 Pascal and 1 atmosphere (atm)?
Both are units of pressure, but they have different scales. One standard atmosphere (atm) is defined as the average atmospheric pressure at mean sea level. The relationship is: 1 atm = 101,325 Pa or approximately 101.3 kPa. While 'atm' is a convenient unit for Earth's atmospheric conditions, the Pascal (Pa) is the official SI unit used for universal scientific calculations.
