1. Explaining ideal gas
behavior
Elastic and Inelastic collisions

2. Explaining ideal gas behavior
• Kinetic Energy is the energy associated with the
motion of particles – molecules, atoms, and ions.
Some molecules may posses more than the average
kinetic energy; others may have less than the
average kinetic energy. It is the average kinetic
energy that is proportional to absolute
temperature, the more kinetic energy the substance
has and the more rapidly the particles move

3. Elastic and Inelastic
collisions
• A ball bouncing on the ground loses
some kinetic energy on collision. The
lost kinetic energy changes into heat
as a result of friction.
• The ball thus gradually slows down
until it comes to rest. Collisions with
loss of Energy are term Inelastic.

4. Inelastic collision
• Perfectly elastic collisions are those
in which no kinetic energy is lost in
the collision. Macroscopic collisions
are generally inelastic and do not
conserve kinetic energy, though of
course the total energy is conserved.
The extreme inelastic collision is one
in which the colliding objects stick
together after the collision, and this
case may be analyzed in general

5. Inelastic collisions

6. Kinetic energy lost in
Inelastic collisions

7. Elastic collision
• If collisions between gas particles involved
friction, the molecules would gradually
slowdown and lose kinetic energy
• The gas pressure would slowly drop to
zero. However, this is never observed of
gases. We can thus, postulate that
molecular collisions in gases are
frictionless or perfectly elastic.