Invalidating Classical Momentum

1
Invalidating Classical Momentum Consider a
collision in some reference frame.
A particle, mass m, moves to the right at
0.6c. This particle collides with
another particle, mass m, at rest. After the
collision, the particles stick and move together.
What is the speed of the stuck-together particles
after the collision?
Momentum conserved
Collision ?
2
Invalidating Classical Momentum, continued
3
Invalidating Classical Momentum, continued
Now, view the same collision from a train moving
to the right at 0.3c. This means the M particle
is at rest in the new (primed) reference frame.
to the left
ConcepTest 11.1
4
Invalidating Classical Momentum, continued
So, in the primed reference frame, we have
to the right
to the left
CLASSICAL MOMENTUM NOT CONSERVED!!!
(also, no mass conservation, either)