Move the mouse (or your finger) over the graph to read values. After a run, the peak (maximum static
friction) and the sliding value (dynamic friction) are marked. Press ● Record trial to save them.
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Surface
m / kg
θ / °
Fpeak / N
Fslide / N
FN / N
Ff,max / N
Ff,d / N
Slotted masses (200 g each)
Block face down
Real-data noise
How to use this simulation
Choose the surfaces, the number of slotted masses, the pull angle and the pull rate.
Set each value with ▼ and ▲ (hold to go faster; the ↑ ↓ keys or the mouse wheel in the box also work, Shift = ×10), or type a value in the box. ↺ puts it back to its start value. Outside the classroom range the box turns amber ⚠: fine to explore, but the lab can't do this.
Move the pointer over any graph (or tap it): a dashed line shows the values where it cuts each curve, or the values of the nearest data point.
Press ▶ Start pull. The pull grows steadily, like pulling a newton meter slowly.
Press ⏸ Hold to keep the pull constant and see what static friction does.
When the block starts to slide, the hand keeps it moving at a slow constant speed.
Read the peak and the sliding force from the graph, then press ● Record trial.
Repeat for different loads. The Data tab plots Ff against FN; the gradient is μ.
Work through the Tasks tab. Write explanations on your worksheet.
The physics
Static (at rest): Ff ≤ μsFN — friction matches the pull until it reaches its maximum.
Dynamic (sliding): Ff = μdFN
Pull at angle θ: FN = mg − F sin θ, and the horizontal part of the pull is F cos θ.
At rest or at constant speed the resultant force is zero (forces balance).
Model: μ values are typical classroom values. The block face (contact area) does not change friction in this
model — that is what experiments show. The noise switch adds ±2 % random scatter, like a real sensor.
Newton's laws
The badge above the scene says which law applies at this moment: 1st law — at rest or moving at a constant velocity, the resultant force is zero (ΣF = 0); 2nd law — accelerating, ΣF = ma. The table under the free-body diagram adds up the forces (ΣF) and compares them with m a (▾ folds it). Tick 3rd-law pairs to see every force with its partner: the same size and type, in the opposite direction, acting on the other body (the Earth, the floor, the string, the fluid…).