Why This Hooke’s Law Simulation Has No Slider
Why this spring experiment has no slider
Most spring simulations give you a slider. Drag it, and a number labelled “force” changes. The graph draws itself. Nothing has been measured.
In Hooke’s Law – Hanging Masses, force is not an input. It is something the student assembles: a 10 g hanger goes on first, because everything stacks on it, then masses are added one at a time. To find the force, the student converts the hanging mass themselves. To find the extension, they read the spring’s total length off the ruler and subtract the no-load reading. Both of those steps are where the physics lives, and a slider removes them both.
The springs are not interchangeable
There are five, each with a different stiffness and its own elastic limit, and the value of k appears nowhere on screen. Three of them give readings that land exactly on a millimeter division; the other two do not. Groups working on different springs therefore meet the same law through different arithmetic, which is useful when you want them to compare results rather than copy them.
The assignment is fixed: spring C is the same spring in every session and on every computer, so a class can be marked against one answer key.
A spring can be destroyed
Load one past its elastic limit and it stays deformed. The apparatus locks, and the only way forward is to mount a different spring. This is deliberate. Elasticity is a range, not a property, and a student who has ruined a spring has learned where that range ends better than one who has been told.
A note on g
The simulation does not state a value for g, because classes differ. If your students use 10 N/kg the spring constants come out as whole numbers; with 9.8 N/kg every result is 2% lower and consistent to two decimal places. Either is correct, and the conclusion is unaffected – but decide before the class starts, because mixed conventions in one set of reports are hard to mark.