Physics Spl

The chapter consists of fundamental topics that are important for board exams preparation as well as for competitive tests: 

• Composition and Size of the Nucleus: Understanding protons, neutrons, and nuclear density.

• Nuclear Force: The forces that hold the nucleus together. 

• Mass-Energy Equivalence (E = mc²): Einstein's equation and its significance in nuclear reactions.

• Nuclear Binding Energy: Understanding nuclear stability and energy release. 

• Radioactivity: Concepts of alpha, beta, and gamma decay. 

• Laws of Radioactive Decay: Half-life, mean life, and decay constant derivations. 

• Nuclear Fission and Fusion: Their role in power generation and astrophysical processes.

• Applications of Nuclear Physics: Uses of radioisotopes in medicine, industry, and archaeology.

Hooke's Law states that within the elastic limit, the stress applied to a material is directly proportional to the strain produced. Mathematically,  

E stands for the modulus of elasticity also called Young's modulus in case of linear deformation.
The Hooke's Law defines the elastic behaviour of materials, determines its elastic limit and helps in material selection for construction and manufacturing. It is used to design springs and elastic components in machines. Hook's law is applicable for the solids within their elastic limit. 
Hooke's law for a spring and other elastic material is shown as:

F is the force applied on the material, k is the spring constant i.e. the stiffness of the material and it depends on the material's geometry and properties, and x is the extension or compression produced.

While studying the mechanical properties of solids, stress and strain are fundamental concepts.

Stress: It refers to the condition when the external force is applied to a solid body and it experiences an internal restoring force per unit area. The resisting deformation due to the internal force is called stress. The formula is:

The SI unit of stress is N/m² (Pascal, Pa).

There are three types of stress -

1. When the applied force increases the length of the body, it is called tensile stress.
2. When the applied force decreases the length of the body, it is termed as the compressive stress.
3. When the force is applied tangentially and creates deformation in shape, it is called shear stress.

Strain: It is a dimension less quantity. It refers to the relative deformation produced in a body due to applied stress. The formula is:

There are three types of strain:

1. Change in length per unit original length is called the Longitudinal Strain.
2. The change in volume per unit original volume is called the Volumetric Strain.
3. Angular deformation due to shear stress is called Shear Strain.

Hooke's Law relates stress and strain by a formula. It states that within the elastic limit, stress is directly proportional to strain:

E stands for the modulus of elasticity.

In Newton's Law of Gravitation, G (Universal Gravitational Constant) has a fixed value as it is a fundamental constant which is:

G determines the strength of gravitational interactions and it remains the same everywhere in the universe. It plays a significant role in cosmology and astrophysics and it is important in calculating the forces between celestial bodies. Due to the gravitational pull of a massive body like Earth, 'g' (Acceleration due to Gravity) is the acceleration which the object experiences. The value of g changes based on the planetary composition, latitude, and altitude. G is universal and g is dependent on the location. This relation can be understood by the following formula:

M represents the mass of the planet, and R is the radius. The concept and its differences help in fields such as space exploration where astronauts experience microgravity in orbit even though the gravitational forces are present.