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DEMO 2:TwISTING WEIGHTED METERSTICKS What to do: Hold one meterstick from the ce

ID: 2073779 • Letter: D

Question

DEMO 2:TwISTING WEIGHTED METERSTICKS What to do: Hold one meterstick from the center with one hand and twist it a few times before putting it down. Then pick up the other meterstick and do the same tiling to it Questions 1. Which meterstick is harder to twist? What is different about that stick? 2. These two metersticks have the same total mass, what do you think makes one of them much harder to rotate? What to do next: Hold each meterstick from one of its ends and twist it a few times. Question: is twisting from the ends harder or easier than twisting from the center? Does this experience support your explanation above?

Explanation / Answer

The second meter stick is harder to twist because of the weights wrapped at center. Doing this increases the radius at center and hence increases the section modulus of stick

(more there section modulus more is the resistance to twisting.)

Twisting at the end is easier compared to twisting at center

Because the greater length requires less torque.

T/J=g (theta)/L=shear stress/outer radius