1. Convert Equation 2 to an expression in terms of rpm instead of rad/s. Rearrange the equation to give the maximum rpm that can be applied without failure for a material with yield stress sy.
2. Estimate the yielding stress of your blu-tack using a circular cross-section sample and weights/scales. Report three measurements.
3. Assume the density of blu-tack is ~2500 kg/m3 (check this if you have time) and use your equation to estimate the maximum rpm we can expect for a disk of radius R=_____________ mm.
4. Roll out a sheet of blu-tack, punch out a disk with your specified radius, assemble a flywheel for testing on an electric drill and determine the approximate critical rotation speed in rpm. Comment on the outcome.
5. Derive the material index for a light flywheel that stores the most energy per unit mass and that does not yield when spinning. The rotation speed (angular velocity) and geometry do not matter. Identify the constraint, the objective and the free variables. (Hint: establish the energy per unit mass, then eliminate the free variables). Use the relevant chart or the CES software to establish an optimal material - provide a few sentences of explanation.
6. Ignoring the chance of failure and the weight, derive a material index for a flywheel that stores the most energy per unit volume. Use the relevant chart or the CES software to establish an optimal material - provide a few sentences of explanation.