well, I have tried many ways to get the solution to this problem, but i have two great obstacles: We have atwood's machine with to masses m1 and m2, machine is accelerated upwards with an acceleration a. Find accelerations a1 and a2 for masses m1 and m2 respectively and find the tension. Well, I have wrote the ecuations: -T+(m1)g+(m1)(a1)=(m1)(a) T-(m2)g-(m2)(a2)=(m2)(a) since net force at m1 and m2 are the sum of the forces, including the fictious force introduced because this is a non-inertial system. But I must find a new ecuation because this system has infinite solutions since I have the variables T, a1, a2. where are the other ecuation, or what's the mistake in thinking? Please answer me the fast as it can be possible.