If the bow is dug-into the mud up to the port anchor, then how fast did the Titanic hit the bottom?

Well I am no expert on this, however, if we think about it, the bow section is really more than just the bow, it is two thirds of the ships length. So around 30,000 tons, plus another 30,000 tons of water, so a 60,000 ton lump of metal falling then it must have been going at a grate speed, however, as the water pressure increased then perhaps that slowed down the decent rate to perhaps 40 mph, according to a study I recently read.

40 mph, gosh! That would certainly explain why the decks were pancaked on top of each other (near the split-end of the wreck). Decay over time has most certainly also contributed to this but I read that because the bow was falling so rapidly toward the bottom, a area of lower water pressure was formed above the bow. Like the "vacuum of air" behind a passing bus that feels like it pulls you into the raod. When the bow suddenly stopped at the bottom, a downdraft of water came smack down on top of the ship. This could be the cause for the bridge to be completely flattened.

From what I understand, she hit the bottom pretty hard too.

Yip. It's a mirracle any of the fancy glass windows survived.

The aft end was pancacked because it was pulled under and still contained a lot of air which led to explosive decompression.

The bow was slowly filled with water, this means the bow was neutrally pressurized and didn't have the same problem, that is why it is intact.

A show I watched a few years ago said about 10-12 minutes to descend to the seabed.

The seabed is pretty soft, so it was easy for the bow to dig into the sediment.

Going 40mph in a car isn't that fast

but come to think about it the tianic was heavy which would have made her go down very fast indeed

She could have reached a speed of 50-60 i would have thought

I don't think she would of survived in such good condition at 50-mph. Yes 40mph in a car does't seem to fast, but you are in a shelded enviroment in a car. Try standing through the sun roof at 40mph and it is very different. She may have been going 50-60mph as she wen't down, but the water pressure would of acted as a barrier to slow it down to 30-40mph.

mmm indeed so, the glass would have cetainly been shatered

some of the body structure would have been crushed also

It is eery the way in which certain fragile objects like plates and windows survived the plunge to the bottom. I saw a perfectly preseved jar of olives that was recovered from the wreck and put on display at London's Science Museum in 2003. How could these things have survived sticking the bottom not to mention the intence water pressure?