Game Development Reference
In-Depth Information
+Y
V
2
V
1
M
1
+X
M
2
Figure 12.11
A car crash
as
−1
0
P
= m
1
v
1
+ m
2
v
2
= (1,500 kg)(35 km/hr)
cos 115
o
sin 115
o
+ (2,500 kg)(65 km/hr)
−1
0
−0.423
0.906
= (52,500 kg km/hr)
+ (162,500 kg km/hr)
−52,500
0
−68,700
147,000
−121,200
147,000
=
+
kg km/hr =
kg km/hr.
The resulting velocity of the glob of two cars is simply the momentum we
have just computed divided by the total combined mass:
−121,200
147,000
′
′
v
=
P
/(m
1
+ m
2
) =
kg km/hr
/(1,500 kg + 2,500 kg)
−121,200
147,000
−30.3
36.8
=
kg km/hr
/(4,000 kg) =
km/hr.
12.4.2 General Collision Response
Simple inelastic collisions can be solved by using the principle of conserva-
tion of momentum, but how do we compute the velocities in the general
case? Before we can fully answer that question, we need to consider the
context in which it is asked. Dealing with collisions is typically a two-
step process. First, we must detect that a collision has occurred, meaning
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