How Position Stores Energy That Becomes Motion

"Let me show you something cool. That skateboard sitting at the top of this ramp isn't moving — but it's full of energy. We call it gravitational potential energy (GPE): energy stored because of where the object is positioned, not because it's moving. Two things control how much GPE an object has: its mass (how much matter it contains) and its height above the ground. A heavier board held higher up stores more energy. Now watch what happens when I release it. As the board rolls down, its height drops — so its GPE decreases. But it gains speed. That's kinetic energy (KE): the energy of anything that's moving. Every bit of lost height becomes gained speed. The energy hasn't disappeared; it has transformed. Here's the key idea: GPE and KE are always trading places. At the top of the ramp — maximum GPE, zero KE. Halfway down — some GPE becomes KE. At the bottom — minimum GPE, maximum KE. In this ideal case, the total mechanical energy stays the same the whole way down. In the real world, a small amount becomes heat and sound due to friction, but most converts back and forth between GPE and KE. Then the board shoots up the other side. Speed drops, height rises — KE is converting back into GPE. This back-and-forth is called energy transformation, and it happens in swings, roller coasters, bouncing balls, and countless other systems. Tip for the activity: Just like the skate ramp, a pendulum swings through the same GPE-to-KE trade-off. When you arrange the snapshots, ask yourself — which position stores the most energy ready to become motion?"