1. The problem statement, all variables and given/known data How long should the day be so that the total angular momentum of the Earth (including its rotation about its own axis and its (approximately) circular orbit around the sun) is zero (Note: the magnitude of the angular velocity is 2pi/T where T is the period of rotation?) 2. Relevant equations Ltot = Ltrans + Lrot Lrot = Iw^2 w = 2pi/T 3. The attempt at a solution Ltot = 0 I am really clueless. I don't know where to start..