Friday, April 10, 2015

Physics Life Hack Number 3 - Getting Your Ride Out of a Rut, Without a Tow Truck

This Wrangler isn't stuck, because Jeeps are awesome off-road.

This is a handy trick I've had to use a few times, primarily because of my obsession with driving in places where I probably shouldn't.

Back when I had a Jeep Wrangler and a lust for exploring woodland trails and lonely beaches, I would occasionally find myself literally stuck in a rut, with no other vehicles around to help me out. Sometimes a bit of digging, a few properly place pieces of wood or rocks, or plain old pushing would be enough to free my old jalopy. When that didn't work, it was time to grab the rope and rely on physics to set myself free.


If you're not into physics, you might think to tie the rope to your vehicle, gather as many people as you can find wandering in the brush, and simply pull. That would be the hard, and often impossible, way. A much better way is to use the rope to amplify your own pulling power.

Here's how to do it: tie one end of the rope to the stuck Wrangler (or Miata or Fiesta or minivan or whatever you off-road in) and the other end to a sturdy tree, boulder or post. One key point, though, is to make sure it's a long and very strong rope (I carried a 100 foot long rope with me that was rated to handle nearly two tons). Then don't pull along the rope. Instead find the midpoint and pull perpendicular to the rope, like this.


If you make sure the rope is strung tightly between the tree and the vehicle before you start to pull sideways, this arrangement will amplify your pulling power by as much as ten times. That's like finding ten people to help you pull.

Here are a few physicsy labels to explain what's going on.


This shows the tension in the rope (T1 and T2), the force you apply to pull sideways on the rope (F), and the angle the rope makes as a result of your pulling.

If you happen to like math, and don't want to rely on my words alone, here are the details explaining how much mechanical advantage you gain using this method.


As you can see, you can amplify your effort dramatically, provided the angle the rope makes as a result of your pulling is small. I imagined that you apply 100 pounds of force, which provides over a ton of pulling force for very small angles. If you're stronger than that, or have others to help, you can get a lot more out of it

Clearly, you aren't going to move the vehicle far before the force advantage falls pretty far, though, because as the angle increases the amplification falls. So this technique is best  when all you need to do is move the vehicle a short distance to free it up. Alternatively, you can pull it a bit, have someone wedge something under the wheels to prevent it rolling beck, then tighten up the rope and pull again. It's tedious, but effective.





1 comment:

  1. Intresting decision. I`m not into physics, but this information is quite useful and I`m sure I will remember it for later. Thanks to the author from me.

    ReplyDelete