Elastic Collision
Oct 28, 2022, 16:45 IST
A collision occurs when two objects come into direct contact. It is an event in which two or more bodies exert a force on each other in a relatively short period of time. There are two types of collisions namely:
- Elastic collision
It is one where there is no net loss of kinetic energy in the system due to the collision.
- Inelastic collision
It is a collision where there is a loss of the kinetic energy. The lost kinetic energy is converted into heat energy, sound energy and deformation of the material.
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Definition
An elastic collision is that type of collision in which there will be no net loss in the kinetic energy in the system due to the collision. Both the momentum and the kinetic energy are conserved in an elastic collision.
Elastic Collision Examples
- An example of an elastic collision is when a ball hits another ball at a pool table.
- When you throw a ball to the ground, and it bounces back to your hand, then there will be no net loss in kinetic energy, so it is an elastic collision.
Formula for Elastic Collision
The Elastic Collision formula of momentum is mentioned below:
m1u1 + m2u2 = m1v1 + m2v2
Where,
m1 = Mass of 1st body
m2 = Mass of 2nd body
u1 =Initial velocity of 1st body
u2 = Initial velocity of the second body
v1 = Final velocity of the first body
v2 = Final velocity of the second body
The Elastic Collision formula of kinetic energy is given by:
(1/2) m1u12 + (1/2) m2u22 = (1/2) m1v12 + (1/2) m2v22
Difference between Elastic and Inelastic Collision
| Elastic Collision | Inelastic Collision |
| The total kinetic energy is conserved. | The total kinetic energy of a body at the start and the end of the collision are different. |
| Momentum is conserved. | Momentum is conserved. |
| No conversion of energy takes place. | The Kinetic energy is changed into other energy, such as sound or heat energy. |
| Highly unlikely in the real world as there is almost always a change in energy. |
This is the normal form of collision in the real world. |
| An example of this can be swinging balls or a spacecraft flying near a planet but not getting affected by its gravity in the end. | An example of an inelastic collision can be the collision of two cars. |
Applications of Elastic Collision
The duration of the collision affects the amount of force the object experiences in the collision. The longer the collision time, the smaller the force acting on the object. Therefore, in order to maximize the force on the object during the collision, the time of the collision must be reduced.
The collision time must be increased to minimize the force. There are various real-world applications of these phenomena. Airbags in cars prolong the time of collapse and minimize the force applied to objects in a collision. The airbag achieves this by increasing the time required to stop the momentum of the passenger and driver.
Frequently Asked Question (FAQs)
Q1. What is Elastic Collision?
Ans. It is a type of collision in which there will be no net loss in the kinetic energy in the system due to a collision.
Q2. Why is energy conserved in elastic collisions?
Ans. The simple answer is that in an elastic collision (for objects >> in mass than typical molecules), energy moves from kinetic to potential and then back to kinetic as long as the "elastic limits" of the materials are not exceeded. In other words, as long as they act like springs.
Q3. Why are elastic collisions not seen in nature?
Ans. Unlike the atoms of a liquid or gas, Molecules rarely experience perfectly elastic collisions because, in each collision, there is an exchange of kinetic energy between the translational motion of the molecules and their internal degrees of freedom.
Q4. Is mass conserved in a perfectly elastic collision?
Ans. In an elastic collision, momentum will be conserved in all the quantities we have just defined, mass-energy and kinetic energy.
Q5. What quantity is always conserved in collisions?
Ans. Total momentum is always conserved between any of the two objects involved in a collision. When the moving object collides with a stationary object of the same mass, the stationary object experiences a greater collision force.
