Solving problems in physics, sometimes we use conservation of momentum and sometimes we use conservation of kinetic energy relation when should we use both of the like which all cases can come? Mention all the cases where we use each of these
Answer (1)
10th Jan, 2025
n physics problems, the use of conservation of momentum and conservation of kinetic energy depends on the type of collision or interaction. Here's when to use each:
1. Conservation of Momentum
- Applicable to all types of collisions and interactions.
- Momentum is always conserved in a system where no external forces act.
Common Cases:
-
Elastic Collisions
- Momentum is conserved.
- Kinetic energy is also conserved.
- Example: Billiard balls colliding.
-
Inelastic Collisions
- Momentum is conserved.
- Kinetic energy is not conserved (some is lost as heat, sound, etc.).
- Example: Car crashes.
Perfectly Inelastic Collisions
- Momentum is conserved.
- Kinetic energy is not conserved.
- The objects stick together after the collision.
- Example: A lump of clay sticking to a moving cart.
Explosion Problems
- Momentum is conserved.
- Kinetic energy is not conserved (energy is released in different forms).
- Example: A bomb exploding into fragments.
2. Conservation of Kinetic Energy
- Only applicable in elastic collisions.
- In inelastic or perfectly inelastic collisions, kinetic energy is not conserved.
Common Cases:
-
Elastic Collisions
- Use both conservation of momentum and kinetic energy.
- Example: Two balls colliding with no energy loss.
When to Use Both Conservation of Momentum and Kinetic Energy
-
Elastic Collisions:
- Both momentum and kinetic energy are conserved.
- Example: Collisions between gas molecules in ideal conditions.
Summary:
| Collision Type | Momentum Conservation | Kinetic Energy Conservation | Example |
|---|---|---|---|
| Elastic Collision | Always | Yes | Billiard balls colliding |
| Inelastic Collision | Always | No | Car crash |
| Perfectly Inelastic | Always | No | Objects sticking together |
| Explosion | Always | No | Bomb exploding into fragments |
Comments (0)
