My first question is I wonder why there's no opposite tension acting the towing cable in the diagram above since the two tugboats are dragging the supertanker. I thought if one obeject is dragging another object with a rope, there should be two equal but opposite tension acting on the rope since they are like 'opposing' each other right like the diagram below? Is there any misconception?
My second question is do tensions always exist in pair (equal and opposite) between two objects connected by a rope if one object is dragged? If no, why (please provide me an example if possible)? If yes, what about an object pulled by a force using a rope, is it still two equal and opposite tensions acting on the rope?