| Type |
Conservation
of momentum equation |
Conservation
of energy equation |
| Elastic:
Colliding objects are so hard that no momentum or energy is
lost (such as through shock absorption or the objects sticking together for any length of
time) |
p of objects 1 & 2 before = p
of objects 1 & 2 after X component:
m1v1ix + m2v2ix = m1v1fx
+ m2v2fx
Y component:
m1v1iy + m2v2iy = m1v1fy
+ m2v2fy |
KE of objects 1 & 2 before =
KE of objects 1 & 2 after 1/2m1v1i2+1/2m2v2i2
= 1/2m1v1f2+ 1/2m2v2f2
Since KE is scalar, don't need to consider x and y
components |
| Inelastic:
Colliding objects are not completely hard, so some energy
is lost when objects deform during collision, and objects are in contact for some time. |
p of objects 1 & 2 before = p
of objects 1 & 2 after |
KE is not conserved, but the
total energy is. |
| Completely
inelastic: Colliding objects remain stuck
together after impact. |
p of objects 1 & 2 before = p
of objects 1 & 2 after m1v1
+ m2v2 = (m1 + m2)vf |
KE is not conserved, but the
total energy is. KE of objects 1 & 2
before = KE of objects 1 & 2 after + any energy lost during impact.
1/2m1v1i2+1/2m2v2i2
= 1/2(m1 + m2)vf2 + any energy lost during
impact. |
