Defined experiment and safety
Choose right and up as positive. Applied horizontal forces are modeled separately from any automatic kinetic/static friction. The surface maintains vertical acceleration zero; its normal is N = mg + Fdown − Fup, which is positive for every permitted input. Therefore ΣFy = 0. Horizontal acceleration is ax = (Fright − Fleft)/m. The two-second velocity and displacement estimates assume constant net force and contact throughout the entire interval.
1. Predict, then change one variable
2. Draw only forces ON the chosen block
Arrows are for visual comparison, not precision measurement. Use the table for exact force magnitudes and directions. Velocity is deliberately not drawn as a force.
| Force and source | Horizontal (N) | Vertical (N) |
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3. Controlled-trial notebook
Record at least three cases and make a matched comparison with one variable changed. The numerical prediction is an idealized calculation—not sensor data.
| # | m (kg) | Fright (N) | Fleft (N) | Fup (N) | Fdown (N) | v0 (m/s) | ΣFx (N) | ax (m/s²) |
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4. Seven-Round Force Challenge
Draw seven distinct cases without replacement from an 11-case bank. Calculate horizontal acceleration using signed external force sums and mass. Each choice gives correction feedback; repeated clicks cannot score again.
Select Start to begin the local game.
Score: 0 / 7
Local best: —