You are the captain of a large barge and need to cross a canal in order to transport your barge from the sea to a lake above sea-level.
As you probably know, when you enter the lock, water is added in order to raise the water level until the intended above-sea level is reached.
As you know, this takes a long time.
Really bored, you start to do some math (as all bored people do):
Your barge is $9m\times3m$ long and $3m$ high, with $1m$ submerged in water.
A $1.75m$ long ladder is hanging at one side of the barge, and is used for climbing in the barge.
The lock is a $10m\times10m$ square and it's filled at a rate of $500$ liters per second.
How much time does the water take to reach the hanging ladder?