Transcript Slides for BL Lesson 8_Dynamics 4 Collisions

I figured it out
already. Need
three laws
only.
Blended Learning Lesson 8
Dynamics 4: Collisions
Principle of Conservation of
Momentum
• The total linear momentum of a system is
conserved if no net external force acts on
the system.
4.8.1 Head-on vs Glancing Collision
Head-on Collision
u
before
v1
after
Glancing Collision
v2
u
before
v1
after
v2
• A head-on collision is one in which the
directions of motion before and after the
collision are along the same line of motion.
4.8.2 Elastic vs Inelastic Collisions
• An elastic collision is one all the kinetic energy is
conserved.
• An inelastic collision is one whereby there will be
a lost in kinetic energy.
• A perfectly inelastic collision is one where the 2
objects coalesce (stick together) and move with
common velocity after the collision.
Note: A perfectly elastic collision represents the
maximum possible loss of kinetic energy. It does
NOT necessarily mean all the KE is lost.
Elastic Collision
Inelastic Collision
Relative
Velocity
With respect to BLUE sphere
(i.e. from the frame of the blue sphere)
Total Final KE < Total Initial KE
(KE converted into internal energy,
deformation energy, etc)
Total Initial KE = Total Final KE
Relative speed of approach =
relative speed of seperation
VA=VB
after collision
(maximum loss in KE)