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Grade 12Mechanics

A circular disc made of iron is rotated about its axis at
a constant velocity co. Calculate the percentage change
in the linear speed of a particle of the rim as the disc
is slowly heated from 20°C to 50°C keeping the angular
velocity constant. Coefficient of linear expansion of iron
= 1-2 x 10 5/°C.

Question image for A circular disc made of iron is rotated about its
Profile image of aravind
9 Years agoGrade 12
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1 Answer

Profile image of deepak
9 Years ago
let the radius of the disc at 200c be r0
then at t=500c the radius will be,
r=r0(1+1.2X10-5(50-20))
=>r=r0(1.00036)
 
at t=200c
c0\omegar0
 
at t=500c
c = \omega r =\omegar0(1.00036)
 
hence
c/c0 = 1.00036
in percentage the change is 0.036% from c0
 
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