Help your child compare initial speed and spinning duration as two different observations.
Drag a gold weight, or use the weight slider.
Weight far from the middle is harder to get spinning. It is also harder to slow down. With the same starting energy, this wheel starts slower but spins for longer when its weights are farther out.
Stay with your child throughout the experiment. Read the task together, compare your predictions and start the test. Operate the controls, then discuss what changed.
Ask two separate questions: “Which started faster?” and “Which kept going longer?” Keep Starting energy and Bearing rubbing the same when comparing positions.
Ask: “What did you change? What did you notice? What will you try next?” A different result is a clue, not a bad score.
The wheel spins on an axle. It does not wobble like a free-standing spinning top. A hand flick is less repeatable than the equal starting energy used here.
Use the simulation to discuss patterns. You remain responsible for choosing and supervising any physical activity; real results can differ.
How could we compare two positions fairly without changing the starting energy?
This comparison holds starting energy constant. A hand flick is not repeatable in that way; a slower start can still accompany a longer spin in this model.
This is a balanced flywheel on a fixed axle, viewed from above. The disc is 60 g with a 90 mm radius. Four 12 mm-radius weights move symmetrically. I = ½MR² + 4m(r² + ½a²); ω₀ = √(2E/I); ω(t) = max(0, ω₀ − τt/I). Spin time is Iω₀/τ. Friction torque is constant, so total turns E/(2πτ) stay the same at fixed energy and friction. No wobble, air drag or flexible axle is simulated. Playback is 4× real time.
MIT · Rotational motion
Sources explain the physical relationships. The chosen model parameters and simplifications are listed above.
Quick guide: s = seconds · m = metres · cm = centimetres · g = grams · kg = kilograms.
Think of opening a door. Where the weight sits matters, not just how much there is. Moving the weights outward makes this wheel harder to speed up or slow down.
Cut a cardboard disc and mark four equal distances from the centre. Attach four identical small washers securely. Support the centre on a blunt axle with adult help. Compare inside and outside positions. A hand flick does not deliver exactly the same energy each time.