Everyday Physics

Sometimes, it isn't whether you can set a thing in motion so much as whether you can stop it once it gets going.

Let's say you had a boat on a trailer that you needed moved just a little ways? You might find that you and a friend had enough strength to pull it and turn it and get it moving. And you might decide you didn't NEED to hook it up to the pickup with the trailer hitch to do this little job. So you might go to pulling and tugging and get it in motion moving down the road and all might be well and good as you settle it into the new place you want it to be. If things work out that way and you got lucky.
But if things go a little amuck, and the trailer starts to roll on its own and starts to head in the direction gravity wants it to go that differs from where you want it to go, will the two of you have enough body weight to grab hold and stop it? Or will the best you can do be to get the hell back from it, avoid serious injury or death, and just let it go until it reaches its natural conclusion to the application of gravity and potential energy. Pick up whatever pieces remain to be picked up in the end.
Or let's say you only have the little Jeep Wrangler and the boat is a big one, one of those nice party barge pontoons, say, but the Jeep sure can pull it if you keep it in low gear. All might be fine there until you get to the curve near the bottom of the hill and the boat starts building up speed and you try to apply the brakes but they just squeal on the road as the boat pushes the Jeep along, finally pulling her sideways into the ditch and tree trunks below.
So when deciding whether to enter into an action, it isn't so much whether you can get the thing started moving along that is the question, but whether you possess the braking power to slow it down or stop it altogether if need be.
And there are no photos, as this really isn't about hauling boats on trailers at all.