Topic 3.1: Translational Kinetic Energy

Name: _______________________________ Date: _______________ Period: _______

Key Ideas

• Kinetic energy: $K=\tfrac12mv^2$, the energy an object has because it is moving. Units: joules (J).
• $K$ is always a non-negative scalar — it can never be negative, and its smallest possible value is zero (at rest).
• $K\propto v^2$ — doubling speed quadruples kinetic energy; tripling speed makes it 9 times larger. Direction never matters, only speed.
• Whenever speed is increasing, kinetic energy is increasing; whenever speed is decreasing, kinetic energy is decreasing — no exceptions.
• Kinetic energy depends on reference frame — speed itself depends on who is measuring it, so the same object at the same instant can have different kinetic energy values for different observers.

Keep This Sheet!

These sheets build into your semester study guide. Keep them in order in a binder or folder — you'll want to flip back through them before quizzes, unit tests, and when AP exam review starts in the spring.