how hard something is to stop
the vector product of mass and velocity
FΔt
What causes a change of momentum
a force that increases the net momentum of a system
A force that comes from somewhere other than the colliding or pushing off objects
a force that does not increase the net momentum of a system.
A force from colliding objects or pushing off
The net momentum of a system is constant in the absence of an external force
Momentum before equals momentum afterward
Two objects collide and all kinetic energy is conserved
Two objects collide, remain independent, and kinetic energy is not conserved
Two objects collide, stick together afterward and kinetic energy is not conserved.