ME 2: Dynamics

Proof required

Link the public repo with 2.003SC problem sets 1–4 (each has explained solutions) and Quiz 1 written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Each problem names its reference frame and writes velocity and acceleration in it.
• Free-body diagrams come before every equation of motion.
• Quiz 1 is marked against its solutions, with the score stated.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of 2.003SC problem sets 1–4 (each has explained solutions) and Quiz 1, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 2: Dynamics, unit 1: Kinematics, Newton's laws and moving frames
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Each problem names its reference frame and writes velocity and acceleration in it.
• Free-body diagrams come before every equation of motion.
• Quiz 1 is marked against its solutions, with the score stated.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with 2.003SC problem sets 5–8 and Quiz 2 written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Moments of inertia are found about the right point, with the parallel-axis step shown.
• Lagrange's equations use stated generalised coordinates and agree with a Newton check on one problem.
• Quiz 2 is marked against its solutions, with the score stated.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of 2.003SC problem sets 5–8 and Quiz 2, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 2: Dynamics, unit 2: Rigid-body rotation and Lagrange's equations
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Moments of inertia are found about the right point, with the parallel-axis step shown.
• Lagrange's equations use stated generalised coordinates and agree with a Newton check on one problem.
• Quiz 2 is marked against its solutions, with the score stated.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with 2.003SC problem sets 9–11 written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Natural frequencies and damping ratios come from the equation of motion.
• Mode shapes are normalised and checked against the eigenvalue problem.
• Answers match the explained solutions, and misses are reworked.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of 2.003SC problem sets 9–11, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 2: Dynamics, unit 3: Vibration of systems with one or more masses
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Natural frequencies and damping ratios come from the equation of motion.
• Mode shapes are normalised and checked against the eigenvalue problem.
• Answers match the explained solutions, and misses are reworked.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with the raw data (or links to it), photos of the set-up, the analysis notebook and the predicted-vs-measured table with uncertainties (under 18 without an adult: a simulation of the same set-up, compared with published values), and a README that says how to rerun it and what limits the result.

What gets checked

• The phyphox data files (or links) are in the repo and the notebook rereads them.
• The table gives predicted and measured period at three lengths and the damping ratio, each with its uncertainty.
• Each gap is explained, and the small-angle error is estimated for the amplitude used.

Common mistakes

• A result that nobody else can rerun from the repo.
• A table with no explanation of the gaps.

Powstik Guide

A measured experiment on a pendulum (your phone in a sock or cloth bag hung from a string) with the phone's own accelerometer or gyroscope recording the swing in phyphox, in a public repo.

Steps

1. Write down what you expect before you start.
2. Predict the period from T = 2π√(L/g), with L from the pivot to the phone's centre. Then refine it with the physical-pendulum formula T = 2π√(I/(mgd)), treating string and phone as rigid: I about the pivot is I_cm + md², and d is the pivot-to-centre distance. Tie the sock shut, double-knot the string, and swing it low over a bed or cushion, starting under 10°. Record at least 30 swings at three lengths (for example 0.4, 0.8 and 1.2 m). Find the measured period, and the damping ratio from the logarithmic decrement of the decaying amplitude. Fill a predicted-vs-measured table with uncertainties and explain the gaps (swing angle, string stretch, air drag).
3. Fill the predicted-vs-measured (or hand-vs-simulated) table.
4. Explain every gap with a cause someone can check.
5. Write the README and ask someone who knows the subject to check it.

README
ME 2: Dynamics — Measure a pendulum's frequency and damping
What I expected:
How to rerun it:
Predicted vs measured:
Why they differ:
Safety: hand tools and eye protection only

What gets sent back

• No predicted-vs-measured table, or no uncertainties.
• Machine tools, welding, pressure vessels, combustion, or springs and flywheels storing dangerous energy without a trained supervisor.

Resources

What a verifier looks for

• The phyphox data files (or links) are in the repo and the notebook rereads them.
• The table gives predicted and measured period at three lengths and the damping ratio, each with its uncertainty.
• Each gap is explained, and the small-angle error is estimated for the amplitude used.
• Check the engineering and the numbers, not just that it exists: do the units, the hand calculation and the table agree?
• Build photos show hand tools only and eye protection worn: no machine tools, welding, pressure vessels, combustion, or springs and flywheels storing dangerous energy (unless a trained supervisor and a proper workshop are shown).

You'll sign in first, then come straight back here.