Let's say I have 2 boxes, one of mass M and one of mass 2M. They are separated by a distance of 1 meter. I drop them from the same height and see that due to the earth's gravity, they accelerate at the same rate towards the ground. Now, I connect them with a meter long bar. I have 3 questions:
If I let them go from an airplane, with the bar connecting one to the other, will they spin as they fall through the air? I think not, because they have the same acceleration.
If I attach them to a wall so that the bar isn't allowed to fall, and I put the pivot point right in the middle of them, can someone please explain (without torque please, since torque states they spin but doesn't really explain why) why is it that they spin? (Read the question below, I think its really similar to this one but states my confusion better).
And just one more thing (this is exactly like the earth question but I think it shows my confusion more clearly). If I'm in space, with the boxes connected by the bar but the bar not attached to anything, and I attach little rockets to each of the boxes so that the rockets fire in the same direction, my intuition tells me in order to keep it from spinning the rocket on the smaller mass M must be exerting half the force than the rocket on the bigger mass 2M in order to give them the same acceleration and keep them from spinning. However, if I then fix the bar on a pivot point in space, what changes depending on where on the bar I put the pivot point if regardless of the pivot point the boxes have the same acceleration? Why is it that if I put it closer to 2M the bar doesn't spin, but if I put it smack in the middle or closer to M the bar spins? Again, an explanation without torque would be greatly appreciated.