I have actually tried this, not in tug-of-war, but with moving a stuck car (one end affixed to car, one end to a tree or lamppost or something). In that situation, where the objects aren’t actively adjusting to thwart you, it works quite well!
? Are you saying it’s easier to pull a stuck car out of a ditch if you pull sideways from the direction you want the car to go, than if you pull the car in the direction you want it to go? (If the other end of the rope is fixed to a tree). That’s interesting if true! I’m not sure whether it contradicts the tug o war result.
Yep! It might be easier to visualize with a train on tracks—the rope needs to be parallel to the intended direction of movement. Suppose the rope is nearly perfectly taut and tied to something directly in front of the train. Pulling the rope sideways w 100 newtons requires the perp component of force to be 100, definitionally. But the rope can only exert force along itself, so if it missed being taut by θ radians, it’ll be exerting enough force F that Fsinθ=100. But if the rope is very close to perfectly taut, then sinθ≈θ, so (in the limit), you’re exerting infinite force.
This fades pretty quickly as the rope gets away from the 0 angle, so you then need to secure the car so it won’t move back (rocks under tires or something), and re-tighten the rope, and iterate.
Nice. And I guess the reason it doesn’t work in tug o war is that there isn’t one side that is fixed; instead both sides are exerting roughly constant force and so it continues to cancel out?
That depends on how exactly the experiment was carried out. If both sides reoriented to pull at an angle, then you are not actually pulling sideways anymore, there’s just 3 sides now.
I have actually tried this, not in tug-of-war, but with moving a stuck car (one end affixed to car, one end to a tree or lamppost or something). In that situation, where the objects aren’t actively adjusting to thwart you, it works quite well!
A Spanish windlass works (in part) on the same principle.
? Are you saying it’s easier to pull a stuck car out of a ditch if you pull sideways from the direction you want the car to go, than if you pull the car in the direction you want it to go? (If the other end of the rope is fixed to a tree). That’s interesting if true! I’m not sure whether it contradicts the tug o war result.
Yep! It might be easier to visualize with a train on tracks—the rope needs to be parallel to the intended direction of movement. Suppose the rope is nearly perfectly taut and tied to something directly in front of the train. Pulling the rope sideways w 100 newtons requires the perp component of force to be 100, definitionally. But the rope can only exert force along itself, so if it missed being taut by θ radians, it’ll be exerting enough force F that Fsinθ=100. But if the rope is very close to perfectly taut, then sinθ≈θ, so (in the limit), you’re exerting infinite force.
This fades pretty quickly as the rope gets away from the 0 angle, so you then need to secure the car so it won’t move back (rocks under tires or something), and re-tighten the rope, and iterate.
Nice. And I guess the reason it doesn’t work in tug o war is that there isn’t one side that is fixed; instead both sides are exerting roughly constant force and so it continues to cancel out?
That depends on how exactly the experiment was carried out. If both sides reoriented to pull at an angle, then you are not actually pulling sideways anymore, there’s just 3 sides now.