CSSA 2020 Physics Q35d (1 Viewer)

[carrotsss]

I did the exact same working as them except I used 1.5*10^-3 rather than 2.5*10^-3 for and got



It's a bit weird because they literally imply in the previous solution that r is 1.5*10^-3


Why do they say that r is 2.5cm rather than 1.5cm in (d)?

 

[chilli 412]

surely its 1.5cm because the armature isnt rotating along the other axis (the long one)