Physics · Grades 9–12
Momentum in one-dimensional collisions · Revision sheet
Use signed velocities and a clearly chosen isolated system.
Learn the idea
Momentum
Momentum is mass times velocity, so direction matters. Two opposite momenta may sum to zero.
Conservation
Total momentum is conserved when the external impulse on the chosen system is zero.
Sticking objects
If two objects stick together, their final velocity is common but kinetic energy generally decreases.
Energy distinction
A conserved momentum does not imply kinetic energy is conserved in every collision.
Explain without looking
- Why is a wall not automatically an isolated part of a small collision model?
- A 5 kg stationary cart receives a net impulse of +20 N·s. Find final velocity.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.