How a Lock Works
Did you know that all locks on the Welland Canal
are filled and emptied by gravity? No pumps are used, water just flows
from a higher level to a lower one.
Yes I did. Suppose a ship is sailing from Lake
Ontario to Lake Erie. Then it has to be raised through each lock to a
higher water level. First the ship enters the lock and is secured with
ropes or cables to bollards - those mushroom looking things. Next,
the gates are closed and large valves are opened to allow water from the
canal above the lock to flow through large pipes. The ship begins to
rise. When the water level has risen to that in the canal above the lock,
the gates are opened and the ship sails out.
I thought it would be more
complicated than that.
I heard that it takes
approximately ten minutes for the lock to fill up or empty. We can use
this information to determine the rate at which a lock empties or fills
up.
OK. The rate is the volume of
water required to fill the lock divided by how long it takes to empty or
fill. I read somewhere that you need about 90 000 cubic metres of water
to raise a ship in the lock.
Given the information from Mathise and Geo,
Calculate the rate of flow of water into or out of the lock in metres per
second.
Rate of Flow Solution
It it fast or slow ?
Fast or Slow compared to what ?
How about the number of bathtubs
per second!
Great Idea.
Assume that a bathtub holds 0.035 cubic metres of water.
Using Geo's suggestion, Trig's information and your solution to the
rate of flow problem above, calculate the rate of flow into or out of the
lock in bathtubs per second.
See Bathtub Solution
Holy smoke! Now I know why they
don't want anyone swimming around the locks. You would be sucked down the
pipes.
I guess the most important part of
the lock is the lock gates, since they keep the water at different levels.
I remember reading somewhere that the mass of one door of the upper gate
of the lock is 193 tonnes while the mass of one door of the lower gate is
298 tonnes.
Wow! The lower gate weighs almost
twice as much as the upper gate. I wonder why it weighs so much more?
You should be able to get your
clues from the lock cycle simulation diagram above. Get it?
