Chips In, Chips Out

1. Four chips are already stacked into a tower on a smooth countertop, one on top of the other.
2. Set the controls to slide in 1 chip. Predict how many chips will leave the stack, then run it and describe what happens.
3. Rebuild the tower and repeat with a stack of 2 chips. Predict, run, describe.
4. Rebuild and repeat with a stack of 3 chips. Predict, run, describe.
5. Now change only the force. Try each test again with a very gentle flick, then a very hard one. What is different?
6. Use the Energy transfer panel to fill in your energy diagram: name the source object, name the receiver object, and record which one decreases in energy and which one increases.

Follow up

• Claim: The number of poker chips I flick into the stack of poker chips will ________ the number of poker chips that leave the stack.
• Evidence and reasoning: use your trial log below and vocabulary from class to explain why that happens.
• What happened to the chips that were sitting on top? Which of Newton’s laws explains that?

Newton’s First Law of Motion says an object at rest stays at rest, and a moving object keeps moving the same way, unless an unbalanced force acts on it. Objects resist changes to their motion. That resistance is called inertia.

Why the count always matches

Every chip in this lab has the same mass. When a moving object hits a still object of equal mass head‑on, it hands over almost all of its motion energy (kinetic energy) and nearly stops. So one incoming chip empties itself into one bottom chip, and that chip shoots out the far side. Two incoming chips reach two bottom chips. Three reach three. Chips in equals chips out — the collision passes the energy through, one chip at a time.

Why the top chips do not fly away too

Nothing pushes the top chips sideways. The only sideways force in the whole event happens down at the bottom, between the chips that touch. The chips above have inertia, so with no sideways force on them they do not move sideways — they simply drop straight down when the chip underneath them disappears. Gravity is now unbalanced, so they fall. This is the same reason a tablecloth can be yanked out from under a set table.

Why a slow push ruins it

A hard, fast flick delivers the force in a tiny fraction of a second, so only the bottom chips ever feel it. A slow push spreads the force through the entire tower, and the whole stack gets shoved along the counter together. Because the bottom starts moving while the top “wants” to stay still, the tower leans and topples — inertia again, just showing up in a different way.

Following the energy

• The source object is the chip or chips you slide in. They start with motion energy and lose almost all of it.
• The receiver object is the chip or chips knocked out. They start with zero motion energy and gain a large amount.
• The energy does not perfectly balance. About a fifth of it turns into sound and heat — that is the click you hear. Energy is never destroyed, but it does get spread out into forms you cannot use.
• Friction with the counter is what eventually stops the knocked-out chips. A harder flick means more motion energy, so they slide farther before friction uses it all up.

1. Choose 1, 2, or 3 chips to slide in. The white chips on the left are the ones you are sliding.
2. Drag the force slider from 1 to 10 to set how hard you flick. The words underneath tell you the speed that flick produces.
3. Pick a prediction for how many chips will leave the stack. The simulation checks it for you afterward.
4. Set the playback speed. A real collision lasts a few thousandths of a second, so use Slow or Super slow to actually watch the chips swap places.
5. Press Slide the chips and watch the bottom of the tower. Count how many chips shoot out to the right.
6. Check the big chips in → chips out comparison under the countertop, and read the Energy transfer panel for the real numbers you need for your energy diagram.
7. Press Rebuild the tower, change one thing, and run it again. Every trial is saved in the log below.