Height into Motion

OKAY, BUT… HOW? · A closer look

Question: What does a higher starting point give a marble?

You’ll be able to: Compare two release points and identify which supplies more energy from the drop.

A marble held above the finish has stored energy because of its position relative to Earth. Let it go without a shove: gravity can turn that stored energy into movement as it descends.

For the same marble near Earth, a bigger vertical drop supplies more gravitational energy. Measure straight down between the marble’s center at the start and its center at the finish. The winding route between them is a different measurement.

Quinn can move his release mark down the same ramp while keeping the finish in place. That reduces the drop. It gives him a useful energy comparison, but whether his particular cup holds the marble still needs an actual trial.

Diagram in words: Quinn points across the branded header above two release marks on one downhill ramp. Mark A is higher than B; both share a finish. Vertical arrows from the marble centers show a larger drop from A and a smaller drop from B.

Open the full-resolution diagram

Try the idea

Look at A and B. The marble and finish stay the same. Which release supplies more gravitational energy, and what measurement settles it?

Answer: A supplies more. Its marble-center height is farther above the finish. You need the vertical separation, not the number of bends or the length of track.

A little further, if you want

Optional: the stored energy belongs to the marble–Earth system. Choosing the finish as a reference makes the height comparison convenient; it does not mean energy vanishes at that height.

See it in action

One More Take — Quinn compares high and low release marks on the same track, then lowers the start when he moves the cup.

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Sources

• MIT: Potential Energy and Conservation of Energy — Endpoint height and energy transfers; sections14.2,14.4.1,14.8.
• OpenStax: Gravitational Potential Energy — Height change and stored energy.

Download this lesson with its diagram and answer (PDF)

Free classroom worksheets

Take the height comparison into class with separate student worksheets and a teacher answer key. All three PDFs are free to download, with no sign-up.

• Middle-school worksheet (PDF, 2 pages)
• High-school worksheet (PDF, 3 pages)
• Teacher answer key (PDF, 4 pages)