A fully elastic collision happens when two objects come in contact without suffering a particular loss of any overall kinetic energy. But, when it comes to inelastic collision, there is little loss of the kinetic energy before and after the collision process, an elastic collision occurs when numerous objects collide and the overall kinetic energy of the system is conserved. The law of conservation of momentum is applicable to all collisions, both the elastic and inelastic collisions. Most collisions that we observe in the physical world result in the loss of kinetic energy in the form of sound and heat energy; therefore, genuinely elastic collisions are impractical. On the other hand, some physical systems lose very little kinetic energy and can thus be modeled as elastic collisions. Sound energy, heat energy and any deformation caused in the objects are all converted from the lost kinetic energy.

Elastic Collision

The term “elastic collision” refers to a collision where both momentum and aggregate kinetic energy conservation are satisfied. This means that there is no dissipative force operating during the collision. All of the kinetic energy of the objects prior to the collision remains in the form of kinetic energy after the impact.

There will be a loss of energy when macroscopic objects collide and they are never totally elastic. Hard and rigid ball collisions, such as those seen in the swinging balls device, are practically elastic.

Elastic collisions are “collisions” wherein the objects do not clash, such as Rutherford scattering or a satellite’s slingshot orbit around a planet. Since the repelling Coulomb force protects the particles from colliding in atomic or nuclear dispersion, the collisions are usually elastic.

Collisions in noble(ideal) gases are almost elastic and this property is utilised to generate formulations for gas pressure in a vessel.

Elastic Collision Formula

m1u1 + m2u2 = m1v1 + m2v2

where m1, m2 are the weights of the two objects.

u1, u2 are the initial velocities of the two objects before the collision.

v1, v2 are the final velocities of the two objects after the collision.

Law of the conservation of kinetic energy

½ m1u12 + ½ m2u22 = ½ m1v12 +½ m2v22 

Applications Of Elastic Collision 

• When you drop the ball on the ground, it immediately bounces back towards you. The ball in motion maintains its total momentum and kinetic energy in this situation; hence it rebounds.
• An elastic collision occurs when two atomic particles hit each other. A complete elastic collision is a collision in which there is zero energy loss after the collision.
• The amount of torque that an object absorbs during a collision is affected by the collision time. The force imposed on the object decreases with the length of time the impact happens. As a result, the collision duration must be reduced to maximise the force an item absorbs during a contact.
• The collision time should be extended to reduce the force. These phenomena have a variety of real-world applications. Automobile airbags shorten the time it takes for a vehicle to collapse and reduce the force applied to items during a collision. Airbag achieves this by lengthening the time it takes for the passenger and driver’s momentum to be stopped.

What Is Inelastic Collision?

The objects in an inelastic collision stick together or travel in the same direction. The entire kinetic energy is not retained in this type of collision, but the net momentum and energy are. 

During this type of collision, the energy is changed into various energy types, such as heat and light, because the two masses follow the law of conservation of momentum and travel in the same path at the same velocity during the phenomena. 

m1u1 + m2u2 = (m1+ m2)v

Comparing the total kinetic energy of two collisions is a fundamental approach to determine whether they are elastic or inelastic. You can describe it as an elastic collision if it keeps the same before and after the impact. A change in total kinetic energy, on the other hand, indicates that the collision was inelastic in nature.

In an inelastic collision, the law of conservation of momentum holds true, but we can’t trace the kinetic energy since some of it is transformed to other kinds of energy. Collisions in ideal gases and dispersing encounters of subatomic particles driven by electromagnetic force approach fully elastic collisions. Some giant collisions, such as gravitational interactions involving satellites and stars in the projectile type, are fully elastic.

Conclusion

A fully elastic collision is one where zero kinetic energy is lost during the contact. In an inelastic collision, a portion of the kinetic energy is converted to different energy during the contact. Because any macroscopic collision between objects converts some kinetic energy into internal energy and other types of energy, no significant effects are perfectly elastic. 

In inelastic collisions, the momentum of an object can be analysed because it doesn’t change; however, the kinetic energy cannot be analysed just before the collision because some of the energy gets converted into other types of energy. Collisions in ideal gases and scattering encounters of subatomic particles deflected by the electromagnetic force approach fully elastic collisions.