Page 154 - Fisika Terapan for Engineers and Scientists

354 CHAPTER 11 Collisions

SUMMARY

PHYSICS IN PRACTICE Automobile Collisions (page 343)

PROBLEM-SOLVING TECHNIQUES (page 353)
Conservation of Energy and Momentum in Collisions

IMPULSE ¢t (11.1)
I Fdt p p
0

AVERAGE FORCE IN COLLISION p p (11.4)
F
¢t

ALL COLLISIONS m v m v m v' m v' (11.6)
1 1 2 2 1 1 2 2
The total momentum is conserved.

ELASTIC COLLISION 1 m v m v m v' m v' (11.7)
2
2
1
1
2
1
2
2 1 1 2 2 2 2 1 1 2 2 2
The total kinetic energy is conserved.
VELOCITIES IN ONE-DIMENSIONAL ELASTIC
COLLISION WITH STATIONARY TARGET
Before: v
0, v 0
1 2
v 1
1 2
x m m 2
1
After: v' v (11.13)
1 1
m m 2
1
v' 1 v' 2
1 2
2m 1
x
v' v 1 (11.14)
2
m m 2
1
INELASTIC COLLISION
Kinetic energy is not conserved.
TOTALLY INELASTIC COLLISION
The colliding particles stick together.
VELOCITIES IN TOTALLY INELASTIC COLLISION
(1, 2, or 3 dimensions).
Before: v and v
1 2
v 1
1 2
x m v m v
1 1
2 2
After: v' v' v CM (11.27)
1
2
m m 2
1
v CM
1 2
x