Atwood Machine with a Massive Pulley

An Atwood machine focused on the gravity-versus-tension balance. With an ideal (massless) pulley the rope tension is equal on both sides and a = (m1-m2)g/(m1+m2): each block carries a weight arrow m g down and a tension arrow T up, and the net (m1-m2)g is what accelerates the pair. A block stops when it reaches the pulley or the floor (no teleport reset), and you can grab and tug either block with the mouse. A toggle switches to the double (compound) machine, where a movable pulley carrying m2 and m3 hangs opposite m1 and the rope tensions satisfy T = 2 T2. An optional pulley-mass slider is the advanced case where the moment of inertia splits the tensions, T1 = m1(g-a), T2 = m2(g+a).