Study Notes
Momentum is the product of an object's mass and velocity, and it is a vector quantity, meaning it has both magnitude and direction. The principle of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it.
- Momentum — the mass of the body multiplied by its velocity. Example: A truck with a mass of 30 kg moving at 2 m/s has a momentum of 60 kg m/s.
- Impulse — the rate of change of momentum, equal to force multiplied by time. Example: A tennis ball hit by a racket experiences an impulse that changes its momentum.
- Conservation of Momentum — in a closed system, the total momentum before a collision equals the total momentum after. Example: When two billiard balls collide, their combined momentum before and after the collision remains the same.
Exam Tips
Key Definitions to Remember
- Momentum is mass times velocity.
- Impulse is the change in momentum.
- Conservation of momentum means total momentum is constant in a closed system.
Common Confusions
- Confusing momentum with force.
- Forgetting that momentum is a vector and can be negative.
Typical Exam Questions
- What is the momentum of an object with mass 4 kg moving at 3 m/s? 12 kg m/s
- How does impulse relate to momentum? Impulse is the change in momentum.
- What happens to the total momentum in a collision? It remains constant if no external forces act.
What Examiners Usually Test
- Ability to calculate momentum and impulse.
- Understanding of conservation of momentum in collisions.
- Application of impulse in real-world scenarios like car safety features.