Video narration
Kabze ke paas dhakka kathin, handle par wahi dhakka aasan. Rotational resistance kul mass se nahi, axis of rotation se doori se bhi tay hota hai. Darwaze ko chhote masses mein baantiye. Har mass, axis se r doori par, a = r alpha paata hai: tau = rF = rma = mr2 alpha. Sab jodne par tau = (Sigma mr2) alpha, yani tau = I alpha aur moment of inertia I = Sigma mr2. Doori squared hai, mass ko door rakhne par asar disproportionately badhta hai.