  Several scenarios used in teaching feature a rolling motion with slipping
that transitions to one without through friction with the ground. We summarise
these transitions by introducing an unknown impulse that is transferred to the
ground. Accounting for this in the conservation of angular and linear momentum,
we can deduce the final state of these scenarios in a compact manner and
without requiring details of the friction. Contrasting this technique with an
explicit calculation of the friction illustrates how collisions and
conservation laws allow to solve problems involving complex interactions by
summarising them. We exemplify our technique with three scenarios: a moving
ball starting to roll, a turning wheel being released on the ground, and a
monowheel breaking.
