1. The problem statement, all variables and given/known data Which of the following formulas is valid if the angular acceleration of an object is not constant? Explain your reasoning in each case. (a) v = rω; (b) atan = r[itex]\alpha[/itex]; (c) ω = ω0 + [itex]\alpha[/itex]t; (d) arad = rω2; (e) K = 0.5Iω2. 2. Relevant equations 3. The attempt at a solution (a) v = rω is derived from s = r[itex]\theta[/itex], where s is the arc length of the circular path, r is the radius and [itex]\theta[/itex] is the angular displacement. s = r[itex]\theta[/itex] is valid for each instant of time, whether the angular accleration is constant or not, so v = rω is valid for variable angular acceleration. (b) Don't know! (c) Not valid as the assumption of constant accleration leads to the formula. (d) Don't know! (e) The formula follows from the combination of K = 0.5mv2 and v = rω. v = rω is valid for any acceleration, so K = 0.5Iω2 is valid as well. Any comments would be wel appreciated!