Elastic and inelastic collisions describe interactions where two objects collide and exchange energy and momentum. In elastic collisions, kinetic energy and momentum are conserved, with no energy lost to heat, sound, or deformation; an example is a hard ball rebounding nearly to its initial height. In inelastic collisions, while momentum is conserved, some kinetic energy is lost, often converting to heat, sound, or causing permanent deformation; for instance, tennis balls losing energy during impact. These principles can be explained mathematically using conservation laws, allowing us to determine post-collision velocities based on mass and initial velocities.
What is the main difference between elastic and inelastic collisions?
In elastic collisions, both momentum and kinetic energy are conserved. In inelastic collisions, momentum is conserved, but some kinetic energy is lost as heat, sound, or deformation.
What happens to the relative velocity of two objects in an elastic collision?
The relative velocity of separation after the collision equals the relative velocity of approach before the collision.
Can kinetic energy be completely conserved in all collisions?
No, kinetic energy is conserved only in elastic collisions. In inelastic collisions, some energy is lost.
In an inelastic collision, what forms of energy can the lost kinetic energy convert into?
The lost kinetic energy can convert into heat, sound, or cause deformation of the colliding objects.
How does the mass of colliding bodies affect the outcome of the collision?
The post-collision velocities depend on the masses of the objects and their initial velocities, as shown in the equations derived from conservation laws.
In an elastic collision, what is conserved?
a) Only momentum
b) Only kinetic energy
c) Both momentum and kinetic energy
d) Neither momentum nor kinetic energy
Answer: c) Both momentum and kinetic energy
What happens to kinetic energy in an inelastic collision?
a) It increases
b) It decreases
c) It remains the same
d) It converts entirely to momentum
Answer: b) It decreases
In an elastic collision between two objects, the relative velocity of approach is equal to:
a) Relative velocity of separation
b) The total velocity after the collision
c) The velocity of the heavier object
d) Zero
Answer: a) Relative velocity of separation
Which of the following is an example of a nearly elastic collision?
a) A car crash
b) A ball dropped on the floor
c) A billiard ball collision
d) A bullet hitting a wooden block
Answer: c) A billiard ball collision
Which physical quantity is conserved in both elastic and inelastic collisions?
a) Kinetic energy
b) Potential energy
c) Momentum
d) Force
Answer: c) Momentum