Kinetic energy is the energy store of a moving object. Use mass in kilograms and speed in metres per second in Eₖ = ½mv². For a fixed mass, doubling speed makes kinetic energy four times larger. Example: A vehicle’s speed doubles while mass stays fixed. Explain the change in kinetic energy. Eₖ is proportional to v², so doubling speed makes kinetic energy four times larger. Rearrange the relationship before substituting if a different quantity is required. Use clear labels. Link cause and effect.