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64 votes
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Does the top of a wheel really move at twice the velocity of the center?

The ends of the ruler will indeed move forward by $20 \,\text{cm}$ with respect to the table. However, the point of contact between the wheel and the ruler will only move by $10 \,\text{cm}$ with ...
Vincent Thacker's user avatar
15 votes

Why are material properties often described by symmetric tensors?

This is a difficult subject and is a controversial one in thermodynamics. In 1851 Stokes noticed that in the generalized linear heat conduction written as $\mathbf q = -\mathbf K \cdot \nabla T,$ if ...
hyportnex's user avatar
  • 19.3k
8 votes

Does the top of a wheel really move at twice the velocity of the center?

Vincent Thacker has explained why your experiment got the results it did. I'm going to explain the actual movement of the wheel. Dissecting the movement of the wheel There are 2 things happening: the ...
AI0867's user avatar
  • 461
3 votes

Why are material properties often described by symmetric tensors?

I think the answer already given is quite deep. I would only add that, at least for rank-2 tensors, with real-valued entries, symmetry makes them Hermitian, which ensures that their eigenvalues are ...
Cryo's user avatar
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1 vote

Doubt in pitch of screw gauge

Consider a screw that has been partially driven into a block of wood. The screw has cut a thread in the wood and the when the screw is rotated the helix of the screw itself remains in the precut ...
KDP's user avatar
  • 4,438

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