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physics help please!?
Calculate the moment of inertia (in kg·m2) of a skater given the following information.
(a)
The 64.0 kg skater is approximated as a cylinder that has a 0.120 m radius.
_____kg·m2
(b)
The skater with arms extended is approximately a cylinder that is 56.0 kg, has a 0.120 m radius, and has two 0.950 m long arms which are 4.00 kg each and extend straight out from the cylinder like rods rotated about their ends.
1 Answer
- Steve4PhysicsLv 755 mins ago
For (a) use the standard formula I = ½MR² = ½*64.0*0.120²
For (b) the wording is ambiguous because it is not 100% clear if the inner end of each arm is taken to be on the axis of rotation or on the surface of the cylinder. The wording implies the former, giving:
Each arm is treated as rod rotating about its end: I = ⅓mL². You add the moments of inertia of the cylinder and the two arms:
I = ½MR² + 2(⅓mL²) = ½*56.0*0.120² + 2(⅓*4.00*0.950²)
You can complete the arithmetic. Remember to round answers to 3 sig. figs.