We were shown this image ^
We were later told that it is suggested that the depression (y), is directly proportional to the length of the beam cubed (L3). We were asked to give reasons why this is so.
EDIT: The 1kg mass is placed at L/2
y is directly proportional to L3
The Attempt at a Solution
I am rather confused, I think moments may be involved and we were told to consider the force acting on the metre rule. I know it isn't much of an attempt, but any guidance in the right direction will be extremely grateful.