Stress in Physics: Definitions, Examples, History, Stress Units, Types, Stress Formula, Hooke’s Law, and Applications

Stress in Physics Overview 

Stress is a physical term that describes the amount of force applied to a material per square inch. Stress, which results from externally applied forces, is a physical science and engineering term for force per unit area within the material. The breaking stress, also known as the ultimate tensile stress, is the highest stress a material can withstand before breaking. Tension is what causes a substance to be tensile. The material is attempting to be stretched by the forces at work. There is an internal restoring force produced when the elastic bodies take on their original form. The restoring force is stress if we attempt to calculate how much it exerts per unit area on the deformed body. Compression occurs when a body is being squeezed by external forces. 

What is Stress?

An item deforms when the deforming force is applied to it. An opposing force will be produced inside the item to return it to its original size and shape. This restoring force will have the same magnitude as the applied deforming force and will be applied in the opposite direction. Stress is a term used to describe how much of this restorative force is produced per unit area of the material. Thus, "The restoring force per unit area of the material" is the definition of stress. It has a tensor value and is represented by the Greek letter sigma (𝝈). measured in N/m² or Pascal. Presented mathematically as -

𝞼 = F/A

The restoring force, or F, is expressed in Newtons or N.

A represents the cross-sectional area in m².

The stress is calculated using either N/m² or Pa.

Real-Life Stress Examples

Several examples of how stress is used in our daily lives are as follows-

1. Everything from the foundations to the support beams to the columns incorporates the notion of stress and how it impacts the various components of the structure.
2. The concept of stress is used in architecture to plan the construction of a building. 
3. The concept of stress is utilized to create numerous day-to-day tools that we use in our everyday lives, etc.
4. The notion of stress is employed in the design of automobiles, spaceships, airplanes, and fighter planes, among other things.

Read more about the Cohesive Forces, Frictional Force, and Lorentz Force.

Highlights of Stress in Physics

The following table gives details about the stress in physics-

History of Stress in Physics

Since the beginning of time, humans have been aware of internal tension in materials. This understanding was primarily intuitive and empirical up until the 17th century, but this did not stop the creation of highly sophisticated technologies like composite bow and glass making. With clever devices like the capitals, arches, domes, trusses, and flying buttresses of Gothic cathedrals, architects, and builders, in particular, have learned over many millennia how to assemble carefully shaped wood beams and stone blocks to withstand, transmit, and distribute stress in the most effective way.

Stress Units in Physics

Given that pressure is a dimension of stress, the coordinates of stress are measured in pascals (Pa, or newtons per square meter) in the international system or pounds per square inch (psi) in the imperial system. The unit of mechanical stress known as MPa, or megapascal, is frequently used because mechanical stresses frequently reach one million Pascals. Multiple units can be used to describe stress. The table below contains the stress units-

Types of Stress in Physics

Although there are many different kinds of stress in physics, they are primarily divided into two types: Normal Stress and Tangential or Shearing Stress. The following are a few different forms of stress-

Normal Stress

The normal force is the stress that results from applying an axial force to a component. To put it another way, when the stress applied to the body is perpendicular. The object's stress level returns to normal when its length and volume are changed. It stands in for the sign. In the SI system, normal stress is measured in millipascals (MPa).

Formula of Normal Stress

Normal Stress = Axial Force / Cross-sectional Area

Normal stress arises when an item is in tension or compression. Normal stress is further divided into two categories-

Longitudinal Stress is further divided into 2 types-

Shearing stress or tangential stress

Shearing stress or tangential stress is defined as a force applied tangentially over the surface area of a plane. The surface is considered to be tangent when the forces acting on it are parallel to it and the stress acting on it follows a tangent. This sort of worry is known as shearing stress.

Stress Formula in Physics

The formula for calculating the stress applied to a body is as follows-

Stress = (Restoring Force) / (Area of Material)

As a result, we utilize notation to represent stress.

Stress in Physics: Hooke’s law

Hooke's law states that when a material is loaded within its elastic limit, the stress created in the body is directly proportionate to the strain produced. Thus, within the elastic limit, the stress-strain ratio is constant. The modulus of elasticity, modulus of rigidity, or elastic moduli is the name given to this constant.

Applications of Stress in Physics in Real Life

Every day, professions like mechanical engineering and architecture use the idea of stress. Here are a few general instances of how stress is used-

1. In architecture, the idea of stress is utilized to develop a building's structural layout. 
2. Mechanical engineering and industries like robotics also make extensive use of stress. 
3. The notion of stress and how it impacts the various sections of the building is included in every aspect of the structure, including the building's foundation, support beams, and columns.
4. To avoid any accidents, it is essential to understand how various mechanical components could put stress on one another.

Points to Remember

1. Normal stress and Shearing stress are the two main forms of stress.
2. Longitudinal Stress and Bulk Stress are the two categories of normal stress.
3. The external restorative force applied per unit area of a body is described as stress. 
4. The magnitude of forces that create deformation in an item is described by stress.
5. The Stress Formula is stated as = F / A, where F is the applied force and A is the area on which the force acts. 
6. The stress symbol is and it is a scalar quantity.

Sample Questions of Stress in Physics

Sample Question 1: In the event of shearing stress, what is the direction of the deforming force? 

Solution: The deforming force in shearing stress is parallel to the cross-sectional area.

Sample Question 2: What is the stress unit? 

Solution: N/m2 or Pascal is the SI unit of stress.

Sample Question 3: Define long-term stress. 

Solution: Longitudinal stress is the stress that an item experiences throughout its length when equal and opposing deforming forces perpendicular to the area of the cross-section are present.

Sample Question 4: What impact does tangential stress have on an object? 

Solution: Tangential tension causes the form of an item to shift.

Sample Question 5: A coil spring's stretching is determined by its shear modulus. How? 

Solution: When a coil spring is stretched, neither its length nor volume change; only its shape does. As a result, coil spring stretching is determined by shear modulus.