One time the pulling cart broke down and we had to switch it for another, but when we took it off the rails we forgot about the "shoe" that is supposed to go between the rail and one of the wheels so it can't move downhill (it was like 1degree of slope so barely recognizable as a slope).
It started moving extremely slowly, and all of us except one tried to hold back the force of the train, which of course was imossible and dangerous. The one who did not try to push it very quickly found the "shoe" and put in place. Initially it did not seem to help at all, the train just continued moving at the same pace, tearing up asphalt with the shoe. It finally came to a stop after about 3-5m(?) which takes a fair bit of time with such low speed, and felt like forever given the situation.
The train tracks headed out into an open road, so it could have been so much worse if it were not for the only person thinking clearly in the situation (he was one of the more experienced in our group).
The only major difference is that they often use a safety air brake system shared across an entire consist (train) that requires “charged” pressure (above atmosphere) to disengage the brake (although I think they have moved to an electronic system that now monitors air pressure in each car individually).
This reminds me of a vivid memory I have. I’d just finished a shift cooking, and out back of our restaurant there were railroad tracks. I had a beer and smoke out there with my shift mate, and a train was rolling by. I thought it would be fun to practice jumping on the train. So I do a few passes jogging alongside it, hopping on and off. Then my buddy, standing still, reached out and grabs a rung of a ladder on one of the cars. It immediately picked him up, but he gripped harder due to being startled. He got ragdolled through the air about 10 feet from where he was initially standing.
Kids, don’t play with trains (trespassing issues aside).
Trains are very scary stuff even when moving at a crawl.
A 110,000 ton ship collision is something the human brain is just not going to understand intuitively.
Yes, hence warnings to amateur boat users (e.g. on a canal boat) not to try to stop a collision with the bank using your arms or legs.
[Edit] Boats can also do things that are unintuitive if you are used to driving a car. E.g. turning round the centre of gravity when you steer rather than following the front wheels.
People would think they could stop them like soccer balls, and lose a foot.
I don't know what sort of speed ships travel in harbors (though I know that they are faster than they appear.) In this case, it was an ebb tide (though within an hour of the low) which might have added something to the ship's speed.
https://tides.willyweather.com/md/baltimore-city/patapsco-ri...
Good estimation! :)
For another comparison, Wikipedia gives an estimate of "Apollo 11 launched from Earth to orbit" at 495 million N s [1]. So this is a momentum that's order-of-magnitude comparable to space launches.
Ship KE = 0.5 * (114000 short tons) * (7.5 knots)^2 = ~7.7e8 J.
747 KE = 0.5 * (510,000 lbs) * (560 mph)^2 = ~7.25e9 J.
747 avg weight = (MTOW + OEW) / 2 = ~510,000 lbs
The MV Dali (IMO#9697428) is a little over 95000 GT, or ballpark-ish probably around 114000 tons loaded (and it seems to have been loaded, which would make sense on departure). If it was going even 5kn (2.6 m/s) that'd be about 300 million newton-seconds, or about 3.3 times the momentum of a large jumbo jet like a 747 shortly at cruising speed (around 560 mph). It'd still have the same momentum as said jet if it was going just 1.5kn. The ship of course is enormously more stoutly built and the force is going to be transmitted far more directly into whatever it hits vs into explosions driving mass elsewhere.
I've read that both on water and in space for that matter enormously massive objects moving very slowly messes with human perception and "common sense", it "feels like" something moving along smoothly and slowly should be stoppable or come to a stop. Enormous momentum and forces can be terrifying things.