Energy is just a number which never changes no matter what happens to the system . And anything in physics that remains a constant is considered very important.(it gets a name to itself)!!This number when possessed by a moving body is called kinetic energy.
Always some energy is utilised(or lost) in doing some work.
Use this basic theorem :
Work (by external forces) + Work(by internal conservative forces)+Work(by internal non-conservative forces) = change in the kinetic energy of the system.
Where ,
Work (by internal conservative forces) = negative of the change in potential energy .

now if work by external forces and by internal forces are zero then it becomes the law of conservation of mechanical energy--

change in K.E + change in P.E = 0

Kinetic Energy Problems in Physics
Kinetic energy is the energy possessed by an object due to its motion. Solving problems related to kinetic energy involves using formulas and understanding the relationship between kinetic energy, mass, and velocity.

Key Points:
- Kinetic energy (KE) is calculated using the formula: KE = 0.5 * mass * velocity^2.
- The SI unit for kinetic energy is Joules (J).
- When solving problems, it is important to convert all units to the appropriate form before plugging them into the formula.
- Remember to square the velocity when calculating kinetic energy.

Steps to solve Kinetic Energy Problems:
1. Identify the given values:
- Determine the mass of the object in kilograms.
- Find the velocity of the object in meters per second.
2. Convert units if necessary:
- Make sure all units are in the correct form (kg for mass, m/s for velocity).
3. Plug the values into the formula:
- Substitute the mass and velocity into the kinetic energy formula: KE = 0.5 * mass * velocity^2.
4. Calculate the kinetic energy:
- Perform the necessary calculations to find the kinetic energy in Joules.
5. Check your answer:
- Make sure your answer is reasonable and matches the units of kinetic energy.
By following these steps and understanding the concept of kinetic energy, you can successfully solve problems related to kinetic energy in physics.