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Physicists define a physical quantity as a physical property of a material or system that can be measured and defined in terms of its value. A value is a mathematical expression representing a physical quantity that is formed by multiplying a numerical value by a unit of measurement in algebraic notation. n kg is a mathematical representation of mass, where n specifies the numerical value of the physical quantity and kg denotes the unit of measurement (in this case, kilogrammes). There are at least two characteristics that a physical amount shares with another physical quantity. One is the numerical magnitude, while the other is the unit of measurement in which the numerical magnitude is measured.
It is commonly accepted that the phrase physical quantity refers to a quantity of matter (everyone understands what is meant by the frequency of a periodic phenomenon, or the resistance of an electric wire). The term “physical quantity” does not imply the existence of a quantity that is physically invariant. In special and general relativity, for example, length is a physical quantity, but it is subject to variation under the influence of the coordinate system. When it comes to the world of science, the concept of physical quantities is so fundamental and intuitive that it does not need to be expressly stated or even mentioned. It is commonly acknowledged that scientists will (more often than not) deal with quantitative data rather than qualitative data when conducting research. In any typical science programme, explicit reference and discussion of physical quantities is not included. Instead, it is more appropriate for a philosophy of science or philosophy programme to include such material.
Characteristic property of physical quantities
It is possible to distinguish numerous qualities of physical quantities that are related to their attributes, some of which are given below.
There are no physical quantities that may be smaller than zero, with the exception of electrical charge and temperature. Some physical quantities, such as electrical charge or mass, can have a value of 0, while others cannot. As a result, the object is either electrically neutral (has no charge) or massless in these instances (light). Some physical quantities are scalar, which indicates that they have only a value and no direction, but others are vector. Volume, mass, and mole are only a few examples of these quantities. Other physical quantities are vectorial, in which case you must know which way the arrow is pointing in order to comprehend what is happening. The vectorial quantities velocity and acceleration are two examples of vectorial quantities.
Fundamental quantities and derived quantities are the two sorts of physical quantities that can be measured.
Fundamental physical quantities
The physical qualities that we can measure cover a wide range of topics. All of these characteristics are related to the size or composition of an object. These are the seven fundamental physical quantities:
Mass: Objects have mass, which is a quality that tells us how much matter is contained within the thing. A larger amount of substance is contained within a larger volume of space. The force exerted over an object’s mass is referred to as its weight. The terms mass and weight are frequently used interchangeably. When it comes to weight, the calculation is as follows: weight = mass * 9.81m/s2
Length: It is the attribute that tells us how long an object has been in our possession. In relation to the qualities of area and volume, this attribute is important.
Time: This characteristic is related to the flow of events and is always increasing in value. Time, like matter, is one of the qualities that cannot be negatively manipulated. Time provides us with information about the course of events in the cosmos.
Electrical charge: This is a physical quantity that can be either positive or negative, with only the polarity of the charge determining its value. When placed in an electric field, it creates a force to act on the matter being acted upon.
Temperature: This is the attribute of a substance or item that measures the amount of heat present in the substance or object. The movement of the particles in an object is related to the generation of heat.
Mole: When it comes to molecules, this is a constant physical quantity that counts the number of molecules present in a substance. There are an exact number of particles or molecules equal to 6.02214076 10 23 molecules of the material represented by this attribute.
Luminosity: Luminosity is a form of energy measurement, similar to temperature measurement. Luminosity is a unit of measurement for the amount of electromagnetic energy emitted by an object in the form of light per unit of time.
Derived quantities
Derived physical quantities are the attributes of an object that are derived from two elemental physical values. derived physical quantities Derived quantities can result from a relationship between two different physical quantities (for example, area) or from a relationship between two different physical quantities (for example, volume) (e.g. velocity).
Area and volume: They are related to length.
Velocity and acceleration: They are related to length and time.
Density: It is related to length and mass
Weight: It is related to acceleration and mass (in a planet, acceleration is its gravitational acceleration)
Pressure: It is related to force and length (for pressure, the force can be the weight exerted by an object, and the area over which this force acts is related to length)
Conclusion
Physical amounts and units are two very distinct things. Physical quantities are the physical attributes of an object, whereas units are the reference units that we use to quantify the object’s physical properties. Physical quantities can be classified into two categories: elemental quantities and derived quantities. The elemental quantities are used to construct the derived quantities. In addition to mass and time, there are seven fundamental physical quantities: temperature, molecular weight (length), luminosity (intensity), and electrical charge. Velocity, heat, density, pressure, and momentum are some of the physical quantities that can be derived. There are no physical quantities that may be smaller than zero, with the exception of electrical charge and temperature. Physical quantities have a direct relationship with the units of measurement in physics.
Motion in a curved line
When the body moves in a curved path, this is the motion. It’s also two- and three-dimensional motion. As a result, pure translational motion does not have to be in a straight line all of the time. If an object goes in a curved path without changing its orientation, this situation is feasible.
Example. Motion of a projectile
Motion that is translatory (type curvilinear)
A parabolic path is followed by a ball.
The ball in question is thrown from point O and travels through points A and B to arrive at point C, as shown in the diagram. Projectile motion is the name for this type of movement. Curvilinear motion is the nature of projectile motion. To get from point O to point C, the ball is moving in a curved path rather than a straight line.
Conclusion
The number of various perceptions of rotation on the body that may be produced is zero. As a result, when the net force and net torque acting on the body is zero, we can deduce that the rigid body is in mechanical equilibrium. The directions must be taken with suitable sign conventions because the forces and torques are vector quantities.
