Iron Man I: How It Should Have Ended

I guess I'm on a little bit of a video kick: HowItShouldHaveEnded recently did an Iron Man Spoof:

If you haven't seen these then you should watch the Superman one and the Spider-man one to get the running gag of Superman and Batman in a diner.

Sticky Situation

This one's stolen from Guesstimation.

In the second Spider-man movie Spidey stops a six car subway train by attaching his webs to it and pulling it to a stop in 10 or 20 blocks.

How much force does he need to do this?