How to tell cold fronts from warm fronts

An observer that stands still as the electron moves by him, will observe

Explain vector addition, triangle method and parallelogram method

Quantum mechanics applies to subatomic, atomic, nanometer-size, and micrometer-size systems. nanometer, micrometer, and kilometer-size systems. atomic, nanometer-size, and micrometer-size systems. subatomic, atomic, and nanometer-size systems.