1 kg દળની એક પાતળી નક્કર તકતી તેના વ્યાસ અક્ષને અનુલક્ષીને 1800 rpm ની ઝડપે ભ્રમણ કરી રહી છે. 40 s માટે \(25 \pi \mathrm{Nm}\) જેટલું બાહ્ય ટોર્ક લગાડતાં, તેની ઝડપ વધીને 2100 rpm થાય છે. તકતીનો વ્યાસ ________ m છે.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.