We did an experiment with newtons third law where we pushed two carts together and measured the force exerted with a computer. We did it with springs in between the carts first, which showed the force of the carts to be equal. Then we did it with clay attached to collision ends of the carts and the computer read more force on cart A than cart B. Why? Then.... when they had opposite magnets on and we pushed then together there was also more force read on cart A than cart B. Why? With both scenerios we also had cart B be still and we pushed cart A into it. They exerted the same force? Was there human error in this experiment or is there an explanation for it?