1 Answer
In Class 12 Physics, conservation laws refer to the fundamental principles that describe how certain physical quantities remain unchanged in a closed system over time. These laws are essential for understanding the behavior of objects in motion and the interactions between different systems. Here are the main conservation laws:
1. Conservation of Energy
- Statement: Energy cannot be created or destroyed; it can only be transformed from one form to another. The total energy of an isolated system remains constant.
- Example: In a pendulum, potential energy converts to kinetic energy as it swings down, and kinetic energy converts back to potential energy as it rises.
2. Conservation of Linear Momentum
- Statement: The total linear momentum of a system of particles remains constant if no external force acts on the system.
- Mathematical Expression:
\[
\text{Total Momentum before collision} = \text{Total Momentum after collision}
\]
- Example: In an elastic collision, like when two billiard balls collide, their total momentum before and after the collision remains the same.
3. Conservation of Angular Momentum
- Statement: If no external torque is acting on a system, its angular momentum remains constant.
- Mathematical Expression:
\[
L = I \cdot \omega
\]
where \(L\) is angular momentum, \(I\) is moment of inertia, and \(\omega\) is angular velocity.
- Example: When a figure skater pulls in their arms, they spin faster. Their angular momentum is conserved, but since the moment of inertia decreases, the angular velocity increases.
4. Conservation of Charge
- Statement: The total electric charge in an isolated system remains constant over time.
- Example: In any physical process, like the movement of electrons, the total charge in the system is conserved.
These laws are crucial for solving problems in mechanics, thermodynamics, and electromagnetism. They help in analyzing the motion of objects, energy transfers, and the behavior of systems under various conditions.
1. Conservation of Energy
- Statement: Energy cannot be created or destroyed; it can only be transformed from one form to another. The total energy of an isolated system remains constant.- Example: In a pendulum, potential energy converts to kinetic energy as it swings down, and kinetic energy converts back to potential energy as it rises.
2. Conservation of Linear Momentum
- Statement: The total linear momentum of a system of particles remains constant if no external force acts on the system.- Mathematical Expression:
\[
\text{Total Momentum before collision} = \text{Total Momentum after collision}
\]
- Example: In an elastic collision, like when two billiard balls collide, their total momentum before and after the collision remains the same.
3. Conservation of Angular Momentum
- Statement: If no external torque is acting on a system, its angular momentum remains constant.- Mathematical Expression:
\[
L = I \cdot \omega
\]
where \(L\) is angular momentum, \(I\) is moment of inertia, and \(\omega\) is angular velocity.
- Example: When a figure skater pulls in their arms, they spin faster. Their angular momentum is conserved, but since the moment of inertia decreases, the angular velocity increases.
4. Conservation of Charge
- Statement: The total electric charge in an isolated system remains constant over time.- Example: In any physical process, like the movement of electrons, the total charge in the system is conserved.
These laws are crucial for solving problems in mechanics, thermodynamics, and electromagnetism. They help in analyzing the motion of objects, energy transfers, and the behavior of systems under various conditions.