Elastic and Inelastic Collisions

Bozeman Science
30 Mar 201506:10
EducationalLearning
32 Likes 10 Comments

TLDRIn this informative video, Mr. Andersen explores the concepts of elastic and inelastic collisions in AP Physics Essentials. He explains that in an elastic collision, kinetic energy is conserved, allowing objects to bounce back with the same speed before and after the collision. Conversely, in an inelastic collision, some kinetic energy is converted into internal energy, resulting in damage. Through examples and simulations, he illustrates the conservation of linear momentum in both types of collisions and demonstrates how to calculate outcomes, emphasizing the practical application of these principles in real-world scenarios.

Takeaways
  • 🌐 In a completely elastic collision, all potential energy is converted into kinetic energy and then back into potential energy, allowing the object to bounce back to its original height.
  • 🔄 A completely inelastic collision results in the conversion of kinetic energy into internal energy, causing the objects to stick together and not bounce back.
  • 📈 The conservation of linear momentum principle states that the total momentum before a collision is equal to the total momentum after the collision, regardless of whether it's elastic or inelastic.
  • ⚖️ In an elastic collision, both linear momentum and kinetic energy are conserved, meaning the speed of the objects before and after the collision remains the same.
  • 🔧 In an inelastic collision, only linear momentum is conserved, and the kinetic energy is not, as some of it is transformed into internal energy of the colliding objects.
  • 🚗 Real-world car accidents are examples of inelastic collisions, where kinetic energy is converted into internal energy, causing damage to the vehicles.
  • 📊 The simbucket simulation demonstrates the principles of elastic and inelastic collisions using carts with different masses and velocities.
  • 🔢 The conservation of kinetic energy formula (1/2 m v^2) can be used to determine if a collision is elastic, by comparing the kinetic energy before and after the collision.
  • 🎯 For inelastic collisions, the shared velocity after the collision can be calculated using the conservation of linear momentum, which helps in understanding the energy transfer.
  • 🔍 Observing and analyzing collisions, either through simulation or real experiments, can help in predicting the outcomes and understanding the energy transformations involved.
  • 📝 Data collection and classification of collisions as elastic or inelastic can be achieved by applying the principles of conservation of linear momentum and kinetic energy.
Q & A

  • What is the main topic of the video?

    -The main topic of the video is elastic and inelastic collisions in the context of AP Physics essentials.

  • What happens when a ball with 10 joules of potential energy is dropped on a table in a completely elastic collision?

    -In a completely elastic collision, the potential energy is converted into kinetic energy, and after bouncing off the table, the ball returns all that kinetic energy back into itself, allowing it to regain its original height.

  • What is the difference between an elastic and an inelastic collision?

    -In an elastic collision, both kinetic energy and linear momentum are conserved, whereas in an inelastic collision, kinetic energy is not fully conserved and is converted into internal energy of the objects involved.

  • Where does the energy go in an inelastic collision?

    -In an inelastic collision, the energy that is not conserved as kinetic energy becomes internal energy in the objects that collided.

  • What principle is maintained in all types of collisions, according to the video?

    -Linear momentum is always conserved in all types of collisions.

  • How can you determine if a collision is elastic?

    -A collision is elastic if there is no loss of kinetic energy and the speed before the collision equals the speed after the collision.

  • What is the formula for kinetic energy?

    -The formula for kinetic energy is 1/2 m v^2, where m is the mass of the object and v is its velocity.

  • How does the video demonstrate the concept of elastic and inelastic collisions?

    -The video uses the example of matchbox cars colliding to visually demonstrate the differences between elastic and inelastic collisions.

  • What happens to the carts in a completely inelastic collision?

    -In a completely inelastic collision, the carts become connected and move with a shared velocity after the collision.

  • How can you calculate the final velocity of objects in an inelastic collision?

    -You can use the conservation of linear momentum to calculate the final shared velocity (v3) of the objects in an inelastic collision.

  • What are the key points to remember when studying collisions?

    -The key points are to understand the conservation of linear momentum, recognize the difference between elastic and inelastic collisions, and know how to predict and classify the outcomes of such collisions.

Outlines
00:00
🔋 Elastic and Inelastic Collisions

This paragraph introduces the concepts of elastic and inelastic collisions using the analogy of dropping a ball with 10 joules of potential energy. In an elastic collision, all the potential energy is converted into kinetic energy, and the ball can bounce back to its original height, conserving both momentum and kinetic energy. In contrast, in an inelastic collision, the ball does not bounce back, and the kinetic energy is transformed into internal energy within the ball and the surface it hits. The paragraph emphasizes the conservation of linear momentum in all collisions, whether elastic or inelastic, and the rare occurrence of perfectly elastic collisions in real-world scenarios.

05:06
📐 Simulating Collisions with Matchbox Cars

This paragraph discusses the practical demonstration of elastic and inelastic collisions using matchbox cars. It explains how to identify the type of collision by observing the behavior of the cars post-collision. The paragraph then transitions into a simulation of two carts colliding, detailing the initial velocities and masses of the carts. It illustrates the conservation of linear momentum with a calculation showing that the total momentum before and after the collision remains equal. The paragraph concludes with an exploration of how to determine the final velocity in an inelastic collision where the carts stick together, using the conservation of linear momentum to solve for the shared velocity.

Mindmap
Keywords
💡Elastic Collision
An elastic collision is a type of collision where both momentum and kinetic energy are conserved. In the context of the video, it is exemplified by a ball dropping on a table and bouncing back with the same speed, meaning no energy is lost and all the initial potential energy is converted into kinetic energy and then back into potential energy. This is a rare occurrence in real-life scenarios, but it is a fundamental concept in physics for understanding collision dynamics.
💡Inelastic Collision
An inelastic collision is one where momentum is conserved, but kinetic energy is not. This means that some of the initial kinetic energy is transformed into other forms of energy, such as heat or sound, during the collision. In the video, a completely inelastic collision is described when a ball dropped on a table does not bounce back and all its initial energy is converted into internal energy within the ball and the table, resulting in damage and energy dissipation.
💡Potential Energy
Potential energy is the stored energy an object has due to its position in a force field, like a gravitational field. In the video, the ball initially has 10 joules of potential energy because of its elevated position. When the ball is dropped, this potential energy is converted into kinetic energy, which is the energy of motion.
💡Kinetic Energy
Kinetic energy is the energy that an object possesses due to its motion. It is directly proportional to the mass of the object and the square of its velocity. In the video, the conversion of potential energy into kinetic energy is discussed when a ball is dropped, and the conservation of kinetic energy is a key concept in elastic collisions.
💡Linear Momentum
Linear momentum is the product of an object's mass and its velocity in a given direction. It is a vector quantity, meaning it has both magnitude and direction. The law of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it. In the video, the concept is used to predict the outcome of collisions, both elastic and inelastic.
💡Conservation Laws
Conservation laws in physics state that certain quantities, such as energy, momentum, and charge, remain constant in an isolated system. The video discusses the conservation of both linear momentum and kinetic energy in the context of collisions, emphasizing that these laws are fundamental for understanding and predicting the behavior of objects during collisions.
💡Internal Energy
Internal energy is the total energy contained within a system, which includes the kinetic energy of the molecules and the potential energy of the molecular interactions. It is often associated with heat and temperature. In the video, internal energy is discussed in the context of inelastic collisions, where kinetic energy is converted into internal energy, leading to damage and heat.
💡Matchbox Cars
Matchbox cars are small toy vehicles often used to demonstrate principles of physics, such as collisions. In the video, they are used to visually illustrate the difference between elastic and inelastic collisions, providing a tangible example of the concepts being discussed.
💡Simbucket Simulation
A simbucket simulation is a type of physics simulation that uses virtual carts to demonstrate and study the principles of collision, including the conservation of momentum and energy. In the video, the simbucket simulation is used to show how two carts with different masses and velocities interact during an elastic collision, allowing for the calculation and understanding of momentum and energy conservation.
💡Data Collection
Data collection is the process of gathering information and measurements that can be used for analysis to answer questions or test hypotheses. In the context of the video, data collection would involve measuring the outcomes of collisions, such as velocities and energies, to understand and classify the type of collision (elastic or inelastic) and to apply the principles of conservation of momentum and energy.
Highlights

Introduction to elastic and inelastic collisions in AP Physics essentials video 94.

A ball with 10 joules of potential energy dropped on a table would result in a completely elastic collision if it converted all potential energy into kinetic energy and bounced back.

In a completely inelastic collision, a ball with 10 joules of energy does not bounce at all, and the energy is converted into internal energy of the ball and the table.

Most collisions are somewhere in the middle, being somewhat elastic.

Linear momentum is always conserved in collisions, whether elastic or inelastic.

In an elastic collision, kinetic energy is also conserved, meaning the speed before and after the collision is the same.

An example of an elastic collision is demonstrated with matchbox cars, one bouncing off the other.

In a simulation, two 1-kilogram carts with initial velocities of 5 m/s and 2 m/s demonstrate the conservation of linear momentum.

The conservation of kinetic energy is shown with the carts having 16.5 joules of energy before and after the elastic collision.

In an inelastic collision, the carts stick together and move with a shared velocity, making the conservation of kinetic energy formula inapplicable.

The shared velocity after an inelastic collision allows for the calculation of changes in linear momentum using conservation of linear momentum.

A 1-kilogram cart at 5 m/s and a 2-kilogram cart at 2 m/s colliding inelastically results in a shared velocity of 3 m/s.

The ability to predict the outcome of elastic and inelastic collisions is emphasized.

Data collection can be planned using simulations or physical carts colliding.

Classification of a collision as elastic or inelastic based on the conservation of kinetic energy is discussed.

Applying the conservation of linear momentum to solve for final velocity in an inelastic collision is demonstrated.

The video aims to help understand the concepts of elastic and inelastic collisions, their characteristics, and applications.

Transcripts

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Related Tags
Physics EducationCollision DynamicsElastic ImpactInelastic ImpactEnergy ConservationMomentum TransferAP PhysicsMr. AndersenSimulation UseKinetic EnergyInternal Energy