# Velocity Question

Hello,

I recently watched a National Geographic, Megastructures documentary and I have a question, I thought posting it here would be a good idea :)

(its named "Berlin Train Terminal", the part I want to ask about is when they tip over two towers)

this is the image (I took a screen capture from the episode)
http://imageshack.us/photo/my-images/715/megastructuresberlintra.jpg/

they say that the towers are moving at 6 metres per hour. (the speed of tipping over)

how is that numbered determined and measured? is it a specific king of velocity? (like angular, but I don't think angular v is measured in m/s, or in this case m/hr

Thanks a lot for any replies

Last edited:

## Answers and Replies

tiny-tim
Science Advisor
Homework Helper
welcome to pf!

hello arisu4! welcome to pf!
… they say that the towers are moving at 6 metres per hour. (the speed of tipping over)

how is that numbered determined and measured? is it a specific king of velocity? (like angular, but I don't think angular v is measured in m/s, or in this case m/hr

it's probably the speed of the top of the tower …

as you say, m/hr must be an actual speed (not an angular speed)

(and they're using hr instead of s because that's easier to understand at such slow speeds)

That is the velocity measured for arc made in pitch circle of the tower when it is moving, which can be calculated from angular velocity if we know the length of tower by using the formula:

V= ωR
where,
V= velocity
ω= Angular velocity
R= length of tower