Increase in area of disc ∆A‌=A(2α)∆t ‌=π(0.5)2(2×11×10−6)×10 ‌=0.000055π New area of the disc, ‌A′=A+∆A ‌∴‌‌A′=π(0.5)2+0.000055π ‌‌ or ‌πr′2=0.250055πm2 ‌‌ or ‌‌‌r′=0.500055m ‌‌ Increase in moment of inertia. ‌ ‌‌