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Comment by CalChris | Hacker News Reader

A deer weighs maybe pounds 100 lbs. A car weighs maybe 3000 lbs for a 30 to 1 ratio. That sub weighs 1000 times more than a container. That is how momentum works.

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If you hit a 10 ton object and _any_ of the collision is inelastic, that is a tremendous amount of momentum to dissipate. It might not change the speed of the sub much, but it could still cause a lot of damage to the hull which could then injure sailors inside.

Wouldn't the submarine sink if the hull was so deformed that it damaged 10 sailors?

Not if the majority of the damage to the sailors came from them being unexpectedly bounced around the corridors. If they weren't expecting it, they weren't strapped in or otherwise secured.

That all depends on the cross section of the impact area. If you'd hit the container in a corner (extremely unlucky) then that would be highly annoying. But subs are made to survive pretty strong impacts, including using the conning tower to ram through ice layers. They're immensely strong compared to regular vessels due to the kind of forces they are exposed to when diving deep.

Not sure about what deer you've been around - but the deer family have hit definitely weighed about two or three times that.

Saying I've remembered since I started driving: If it's a deer, hit it, better than hitting a tree. If it's a moose, hit the tree, better than hitting the moose.

Total ratio is only relevant if you want to know how much the sub/car slowed down. Kinetic energy is more relevant if you want to know the physical damage sustained.

If you shoot a bullet at a tall wall and a shorter wall, the bullet hole will be the same.

Alternatively, a deer will still ruin the front end of a car with 1000X the mass.

The energy of the impact will be 1/2mdeltaV^2 either way.

Depends on the deer. Mule Deer here that you can find the front yard of your house can be 200-300lbs. And depends on what you mean by, "deer". Are you think about reindeer? Elk? MOOSE? Hitting a moose is gunna be a bad day.

Why would someone refer to a moose or an elk as a deer?

Deer, Elk, and Moose are all part of the Cervid or deer family.

Also, in various parts of the world, the names are commonly used for different specific animals, which can be confusing. What's called a Moose in say, Sweden is called an Elk in Britain. But what we call elk in the US are a different species entirely. Elk in the US are another name for the red deer species, which was once considered merely a subspecies.

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