Coefficient of Kinetic Friction (From Acceleration)
Slide a block down a rough ramp at a known angle; measure the along-ramp acceleration a and recover μ_k = tan θ − a/(g cos θ), averaged over several runs.
Goal
Determine the kinetic friction coefficient μ_k using Newton’s second law along the incline, a = g(sin θ − μ_k cos θ), rearranged to μ_k = tan θ − a/(g cos θ).
Equipment
- Block on rough incline
- Angle indicator (slider)
- Simulated accelerometer
Theory
While the block slides, kinetic friction has magnitude f_k = μ_k N with N = mg cos θ along an incline. The along-ramp component of weight is mg sin θ, so ma = mg sin θ − μ_k mg cos θ and a = g(sin θ − μ_k cos θ). Measuring a at known θ yields μ_k = tan θ − a/(g cos θ).
Procedure
- Read the theory: the model uses a fixed (hidden) μ_k; you choose the ramp angle θ.
- Pick θ large enough that tan θ clearly exceeds kinetic friction so the block accelerates downhill (try θ ≈ 25–40° first).
- Press “Measure acceleration (run & record)”. The block runs a short segment; an onboard sensor returns a noisy reading of the along-ramp acceleration a.
- Each run appends (θ, a, μ_k) with μ_k computed from your readings. Repeat at least 5 times — you may vary θ between runs.
- Take the sample mean of the μ_k column as your final estimate.
- Compare with the reference value and discuss error sources in the conclusion.
Experiment
Constant kinetic μ_k in the model: each run records noisy a; μ_k = tan θ − a/(g cos θ).
Use θ large enough that the block accelerates. Each click runs a short slide and appends one row; take ≥5 runs (θ can vary).
Measurements
| № | Ramp angle θ ° | Acceleration a m/s² | μ_k from a, θ | |
|---|---|---|---|---|
| No measurements yet — take your first reading. | ||||
Data processing
Lab report
Opens the system print dialog — choose “Save as PDF” or your printer. Header and footer are hidden when printing.
Coefficient of Kinetic Friction (From Acceleration)
Generated: 22 Apr 2026, 03:30
Goal
Determine the kinetic friction coefficient μ_k using Newton’s second law along the incline, a = g(sin θ − μ_k cos θ), rearranged to μ_k = tan θ − a/(g cos θ).
Measurement table
| # | Ramp angle θ (°) | Acceleration a (m/s²) | μ_k from a, θ |
|---|---|---|---|
| No measurements yet — take your first reading. | |||
Fit and derived value
Add at least 2 trials to compute the sample mean.
Conclusion
The mean μ_k agrees with the reference value within tolerance. Dominant errors: accelerometer noise, angle reading, assuming constant a and ignoring air drag.
PhysSandbox virtual lab — values come from your session; add your own discussion of error sources.
Conclusion
The mean μ_k agrees with the reference value within tolerance. Dominant errors: accelerometer noise, angle reading, assuming constant a and ignoring air drag.