[S1 Science and up: Momentum]
Conservation of mass is something you've touched a lot of in your first years in secondary school.
What about conservation of energy? It seems like a primary school subject, but it's integral to many of the constructs in today's world.
Potential energy formula: mgh
m = mass, g = gravitational pull, h = height.
Kinetic energy formula: 1/2 m v^2
m = mass, v = speed.
With these formulae, you can work out how constructs are expected to behave, and build better buildings.
... and hopefully never meet the fate of poor Gopal. (you know which Gopal I am referring to.)