Momentum & Elastic Collisions
Interactive 1D collision physics simulator. Explore elastic and inelastic collisions, coefficient of restitution, and live momentum/energy conservation charts.
CONSERVATION OF MOMENTUM
The Law of Conservation of Linear Momentum states that the total momentum of a system remains constant if no external forces act on it (). This is a fundamental law of physics derived from Newton's Third Law. During a collision, the internal forces between the objects are equal and opposite, so their individual changes in momentum cancel out for the system as a whole.
TYPES OF COLLISIONS
In AP Physics 1, we classify collisions based on whether kinetic energy is conserved: 1. **Elastic Collision**: Both momentum and kinetic energy are conserved. 2. **Inelastic Collision**: Momentum is conserved, but kinetic energy is lost (usually to thermal or sound energy). 3. **Perfectly Inelastic Collision**: The objects stick together and move with a common final velocity.
HOW TO USE THIS VISUALIZATION
1. **Set Initial Velocities**: Aim the carts toward each other at different speeds. 2. **Choose Collision Type**: Toggle between Elastic and Inelastic to see the difference in separation velocities. 3. **Track the Momentum**: Watch the momentum bar chart for the system () stay perfectly still while the individual bars ( and ) swap levels.
CORE FORMULAS
AP EXAM CONNECTION
Unit: Unit 4: Linear Momentum (Topic 4.2)
Learning Objective: 3.2.1
COMMON MISCONCEPTIONS
- Thinking momentum is only conserved in elastic collisions.
- Forgetting that momentum is a vector (negative signs for opposite directions).
- Confusion between internal and external forces.
KEY TAKEAWAYS
- System momentum is constant in collisions (no external forces).
- Elastic: and are conserved.
- Inelastic: Only is conserved.
- Recoil is a conservation of momentum problem (initial momentum is zero).
PRACTICE QUESTIONS
Q1 (QUANTITATIVE): A 2 kg cart moving at 4 m/s hits a stationary 2 kg cart and they stick together. What is their final speed?
Show Answer & Explanation
Answer: 2 m/s
Explanation: kg·m/s. Since they stick, . Thus m/s.
Q2 (CONCEPTUAL): Is momentum conserved in an inelastic collision where kinetic energy is lost?
Show Answer & Explanation
Answer: Yes.
Explanation: Momentum is conserved in **all** collisions as long as there are no external forces. Kinetic energy is only conserved in elastic collisions.
DEEP DIVE: RELATED CONCEPTS
Linear Momentum ($ ec{p} = m ec{v}$) is a measure of an object's "motion in progress." It is a vecto...
ELASTIC VS. INELASTIC COLLISIONSIn AP Physics 1, we classify collisions based on whether kinetic energy is conserved. 1. **Elastic C...
THE LAW OF CONSERVATION OF ENERGYThe Law of Conservation of Energy is a fundamental principle stating that energy cannot be created o...
