Friction force

Equipment

• 3D model of a block sliding on an inclined plane
• Incline-angle θ, friction-coefficient μ, and mass m sliders
• Acceleration readout, force vectors, and Reset button

Procedure

1. Find the angle of slip

   Set μ = 0.2, mass 5 kg, then raise «Incline angle θ» until the block just begins to slide. Record the critical angle θ_c and check $\tan\theta_c=\mu_s$: for μ = 0.2, θ_c ≈ 11°.

2. Measure the sliding acceleration

   At a fixed 30° angle, step μ through several values and read the acceleration. Verify $a=g(\sin\theta-\mu_k\cos\theta)$: at θ = 30°, μ_k = 0.2 gives a ≈ 3.3 m/s²; μ larger than tan θ means no slip.

3. Check the role of mass

   With θ and μ fixed, change «Mass m» from 1 to 20 kg. The measured acceleration stays constant because $a=g(\sin\theta-\mu_k\cos\theta)$ contains no m — gravity and friction both scale with m and cancel; press «Reset» and rerun to confirm.

4. Predict before measuring

   Pick θ = 45°, μ = 0.3 and compute by hand $a=g(\sin45°-0.3\cos45°)\approx 4.8$ m/s² before looking at the readout. After checking, tune μ so the block just holds then creeps; record the threshold and relate it to pushing a cabinet: starting is harder than keeping it moving because $\mu_s>\mu_k$.

Simulation

Experiment history

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