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Elastic Collision - Definition, Examples, Difference Between Elastic and Inelastic Collision, FAQs

Elastic Collision - Definition, Examples, Difference Between Elastic and Inelastic Collision, FAQs

Vishal kumarUpdated on 02 Jul 2025, 04:52 PM IST

In an elastic collision, both momentum and kinetic energy are conserved as two objects collide and then separate without any loss of energy to sound, heat, or deformation. This type of collision is ideal and often occurs in systems with low friction, like gas molecules in a container.

This Story also Contains

  1. What is Collision?
  2. Define Elastic Collision
  3. What Is Inelastic Collision?
  4. Difference between Elastic and Inelastic Collision
Elastic Collision - Definition, Examples, Difference Between Elastic and Inelastic Collision, FAQs
Elastic Collision

In the article, we are going to learn what is a Collision, types of collision, Elastic collision, Inelastic collision, the difference between Elastic and Inelastic collision, elastic collision examples.

What is Collision?

Two things collide when they come into direct contact with each other, and there is a change in their momentum and energy that event is called as Collision.

It occurs when two or more bodies exert forces on one other in a relatively short period of time.

Types Of Collision

Collison can be furthur dicided into two types, i.e., Elastic and Inelastic Collision. Now let's understand these types in detail.

Commonly Asked Questions

Q: What is the relationship between impulse and elastic collisions?
A:
Impulse, which is the product of force and time of contact, is related to the change in momentum during a collision. In an elastic collision, the impulse experienced by each object is equal in magnitude but opposite in direction, ensuring the conservation of momentum.
Q: Can rotational motion be involved in elastic collisions?
A:
Yes, rotational motion can be involved in elastic collisions. In such cases, both linear and angular momentum must be conserved, and the analysis becomes more complex, involving moments of inertia and angular velocities.
Q: How do elastic collisions apply to the game of billiards or pool?
A:
In billiards or pool, the collisions between balls are often treated as nearly elastic. This allows players to predict the paths of balls after collisions, which is crucial for strategic play. The smooth, hard surface of the balls and table helps minimize energy loss during collisions.
Q: How does the concept of elastic collisions apply to gas molecules in kinetic theory?
A:
In the kinetic theory of gases, collisions between gas molecules are often modeled as perfectly elastic. This assumption helps explain gas behavior, as it implies that the total kinetic energy of the gas molecules remains constant, which is related to the temperature of the gas.
Q: How do elastic collisions apply to the concept of momentum exchange in particle physics?
A:
In particle physics, many interactions between subatomic particles are treated as elastic collisions. This concept is used to analyze and predict outcomes of particle interactions in accelerators, helping physicists understand fundamental properties of matter and energy at the subatomic level.

Define Elastic Collision

We often wonders that What is elastic collision in Physics? Answer to that question is- "A fully elastic collision occurs when two bodies collide with each other without losing any Kinetic energy." In this type of collision no Kinetic energy is lost. Hence we can say that, in an elastic collision, both momentum and kinetic energy are conserved.

Example of Elastic Collision


Two Biliard balls colliding with each other is an example of a perfectly elastic collision.
There is no change in net kinetic energy when you throw a ball on the ground and it bounces back to your hand, hence it is an elastic collision.

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Characteristics of Elastic Collision:

  • The linear momentum of an object is conserved in an elastic collision.
  • The object's overall energy is conserved.
  • The kinetic energy of the system is also conserved.
  • During an elastic collision, conservative forces are at work.
  • In an elastic collision, the mechanical energy is not transferred to heat.

Super elastic collision

A superelastic collision occurs when potential energy is converted into kinetic energy, In a superelastic collision, the final kinetic energy of the system is more than the initial kinetic energy.

Examples of Super Elastic Collisio

When a firework blasts in mid –air it just disintegrates into many particles that go in various directions. This explosion push the chemical energy stored which in turn raises the kinetic energy of the fragments.

Elastic Collision Formula

In an elastic collision, both momentum and kinetic energy are conserved.

For two colliding objects with masses $m_1$ and $m_2$, and initial velocities $u_1$ and $u_2$, the final velocities $v_1$ and $v_2$ after the collision can be given by:
1. Conservation of Momentum:

$$
m_1 u_1+m_2 u_2=m_1 v_1+m_2 v_2
$$

2. Conservation of Kinetic Energy:

$$
\frac{1}{2} m_1 u_1^2+\frac{1}{2} m_2 u_2^2=\frac{1}{2} m_1 v_1^2+\frac{1}{2} m_2 v_2^2
$$


Using these equations, we can solve for the final velocities of the two objects as follows:
- Final Velocity of $m_1$ :

$$
v_1=\frac{\left(m_1-m_2\right) u_1+2 m_2 u_2}{m_1+m_2}
$$

- Final Velocity of $m_2$ :

$$
v_2=\frac{\left(m_2-m_1\right) u_2+2 m_1 u_1}{m_1+m_2}
$$

Commonly Asked Questions

Q: What is an elastic collision?
A:
An elastic collision is a type of collision between objects where both kinetic energy and momentum are conserved. In other words, the total kinetic energy of the system before the collision is equal to the total kinetic energy after the collision, and no energy is converted to other forms like heat or sound.
Q: Can two objects with different masses undergo an elastic collision?
A:
Yes, two objects with different masses can undergo an elastic collision. The laws of conservation of momentum and kinetic energy apply regardless of the masses of the objects involved.
Q: What happens to the velocities of two objects after an elastic head-on collision?
A:
In an elastic head-on collision between two objects, they exchange velocities relative to their center of mass. If the masses are equal, they simply swap velocities. If the masses are different, the lighter object will experience a greater change in velocity.
Q: How does the concept of elastic collision apply to atomic and subatomic particles?
A:
In atomic and subatomic physics, many collisions between particles are treated as elastic. This is because at these scales, the internal structure of particles is often not affected by collisions, and the total kinetic energy of the system is conserved.
Q: How do elastic collisions relate to Newton's laws of motion?
A:
Elastic collisions obey Newton's laws of motion, particularly the third law (for every action, there is an equal and opposite reaction). The conservation of momentum in elastic collisions is a direct consequence of Newton's laws.

What Is Inelastic Collision?

Inelastic collision occurs when two objects collide together and they lose their initial kinetic energy. This lost kinetic energy of the colliding objects is used to produce another form of energy which includes heat, and sound energy, and also can deform the object permanently.

Example of Inelastic Collision

When two cars collide with each other (accident), large amount of Kinetic energy is converted into heat energy and sound energy, and the bending of the metal of the cars.

Characteristics of Inelastic Collision:

  • Momentum is conserved in an inelastic collision.
  • The complete amount of energy is preserved.
  • The kinetic energy of the system is not preserved.
  • An inelastic collision involves non-conservative forces.

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Inelastic Collision Formula

For a perfectly inelastic collision (where the objects stick together after collision), the final velocity $v$ of the combined mass after collision is given by:
1. Conservation of Momentum:

$$
m_1 u_1+m_2 u_2=\left(m_1+m_2\right) v
$$


Solving for $v$, we get:

$$
v=\frac{m_1 u_1+m_2 u_2}{m_1+m_2}
$$

Commonly Asked Questions

Q: What role does friction play in elastic collisions?
A:
In an ideal elastic collision, friction is assumed to be negligible. However, in real-world scenarios, friction can cause some energy loss, making the collision slightly inelastic. The presence of friction can convert some kinetic energy into heat energy.
Q: Can sound production during a collision still allow it to be considered elastic?
A:
Strictly speaking, if sound is produced during a collision, some kinetic energy is converted to sound energy, making the collision slightly inelastic. However, if the amount of energy converted to sound is negligible compared to the total kinetic energy, the collision can still be approximated as elastic for practical purposes.
Q: How does elasticity of materials affect collision outcomes?
A:
The elasticity of materials determines how close a real-world collision comes to being perfectly elastic. More elastic materials (like rubber) will result in collisions that are closer to perfectly elastic, while less elastic materials (like clay) will result in more inelastic collisions.
Q: Can an elastic collision occur if one object is initially at rest?
A:
Yes, an elastic collision can occur when one object is initially at rest. The moving object will transfer some of its kinetic energy to the stationary object, causing it to move while slowing down itself, but the total kinetic energy of the system will remain constant.
Q: What is the importance of studying elastic collisions in physics?
A:
Studying elastic collisions is important because it helps in understanding fundamental principles of physics such as conservation of energy and momentum. It also provides a simplified model for analyzing more complex collision scenarios and has applications in various fields, from sports to particle physics.

Difference between Elastic and Inelastic Collision

Below table describes the difference between elastic and inelastic collision. Which will help the students to undertsand the key differences in a better way.

Elastic collision
Inelastic collision
The complete kinetic energy of the system is preserved.
The total kinetic energy of the bodies differs at the start and end of the impact.
There is no loss of momentum.There is no loss of momentum.
There is no energy conversion.Kinetic energy is converted to other forms of energy, such as sound or heat.
In the real world, this is highly implausible because energy is constantly changing.In the real world, this is the most common type of collision.
Swinging balls or a spaceship passing close to a planet but not being impacted by its gravity are examples of this.A collision between two autos is an example of an inelastic collision.

Commonly Asked Questions

Q: How does an elastic collision differ from an inelastic collision?
A:
In an elastic collision, both kinetic energy and momentum are conserved, while in an inelastic collision, only momentum is conserved. Inelastic collisions result in some kinetic energy being converted to other forms of energy, such as heat or deformation of the objects involved.
Q: Can perfectly elastic collisions occur in real life?
A:
Perfectly elastic collisions are an idealization and rarely occur in real life. However, some collisions can be very close to elastic, such as collisions between atomic particles or between very hard objects like billiard balls on a smooth surface.
Q: What are the key characteristics of an elastic collision?
A:
The key characteristics of an elastic collision are: conservation of both kinetic energy and momentum, no permanent deformation of the colliding objects, and the objects separating after the collision with their shapes unchanged.
Q: How do you determine if a collision is elastic or inelastic?
A:
To determine if a collision is elastic or inelastic, you need to calculate the total kinetic energy before and after the collision. If the total kinetic energy remains the same, the collision is elastic. If there's a decrease in total kinetic energy, the collision is inelastic.
Q: What is the coefficient of restitution, and how does it relate to elastic collisions?
A:
The coefficient of restitution is a measure of the "bounciness" of a collision. It's the ratio of the relative velocity of separation to the relative velocity of approach. For a perfectly elastic collision, the coefficient of restitution is 1, while for inelastic collisions, it's between 0 and 1.


Frequently Asked Questions (FAQs)

Q: What role do elastic collisions play in the field of quantum computing?
A:
In quantum computing, the concept of elastic collisions is relevant to understanding and controlling the interactions between qubits (quantum bits). While quantum interactions are more complex than classical elastic collisions, the principles of energy and information conservation in these interactions are crucial for developing and optimizing quantum computing algorithms and hardware.
Q: How do elastic collisions contribute to our understanding of planetary formation?
A:
Elastic collisions are important in models of planetary formation. In the early stages of solar system development, small particles collided and aggregated. Many of these collisions can be approximated as elastic, especially for smaller particles. Understanding these collisions helps explain how planets and other celestial bodies formed from cosmic dust.
Q: What is the significance of elastic collisions in the development of fusion energy?
A:
In fusion energy research, elastic collisions play a crucial role. The behavior of plasma, which consists of charged particles, is partly governed by elastic collisions between these particles. Understanding these collisions is essential for designing fusion reactors and predicting plasma behavior under extreme conditions.
Q: How do elastic collisions apply to the field of materials science?
A:
In materials science, understanding elastic collisions at the atomic and molecular level is crucial for predicting and designing material properties. This knowledge is applied in developing materials with specific elastic properties, understanding crack propagation, and analyzing the behavior of materials under stress and strain.
Q: How do elastic collisions relate to the concept of mean free path in gases?
A:
The mean free path, which is the average distance a particle travels between collisions, is directly related to elastic collisions in gases. In the kinetic theory of gases, molecules are treated as undergoing elastic collisions. The frequency and nature of these collisions determine the mean free path, which in turn affects properties like viscosity and thermal conductivity.
Q: What role do elastic collisions play in the functioning of particle detectors?
A:
Particle detectors often rely on the principles of elastic collisions to detect and measure properties of subatomic particles. When a particle elastically collides with atoms in the detector material, it transfers energy and momentum, which can be measured to determine the particle's properties, such as its mass, velocity, and charge.
Q: How does the study of elastic collisions contribute to the field of astrophysics?
A:
In astrophysics, elastic collisions are important in understanding various phenomena. For example, the dynamics of star clusters, the behavior of interstellar gas, and even the formation of galaxies involve processes that can be modeled using principles of elastic collisions, especially when dealing with large-scale, low-density environments.
Q: Can the principles of elastic collisions be applied to understand nuclear reactions?
A:
While most nuclear reactions involve inelastic collisions due to the changes in nuclear structure, the principles of elastic collisions are still important in nuclear physics. Elastic scattering of particles off nuclei is used to probe nuclear structure and properties, similar to how Rutherford used alpha particle scattering to discover the atomic nucleus.
Q: How do elastic collisions relate to the concept of scattering in quantum mechanics?
A:
In quantum mechanics, elastic scattering refers to interactions where the internal states of the particles remain unchanged, analogous to classical elastic collisions. This concept is crucial in understanding phenomena like electron diffraction, neutron scattering, and other quantum-level interactions where energy and momentum are conserved.
Q: What is the significance of elastic collisions in the field of nanotechnology?
A:
In nanotechnology, understanding elastic collisions at the molecular and atomic scale is crucial. It helps in designing nanostructures, predicting the behavior of nanomaterials, and developing nanoscale devices. At this scale, many interactions can be approximated as elastic collisions, influencing properties like thermal conductivity and mechanical strength.
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