After this lesson, you should be able to:

• Distinguish between open and isolated systems
• Distinguish between internal and external forces in relation to open and isolated systems
• State the law of conservation of (linear) momentum and the conditions under which it holds
• Distinguish between elastic and inelastic collisions in terms of conservation of kinetic energy
• Link the conservation of linear momentum to Newton’s third law of motion
• Apply the law of conservation of momentum to collisions and explosions (in cases along a straight line)