While reading some fanfic's on Halo I noticed how ridiculously overpowered the Mac cannon is in Halo if it was real. To show this I will show some numbers (Data on MAC's I got from Halopedia)
The equation for kinetic energy is as follows: EK=1/2mv^2
If a Regular MAC on the Spirit of Fire shoots a 600 kiloton slug at 120,000 kilometers per second that means it produces 4.25 Zetta joules of energy or 4,250,000,000,000,000,000,000 joules
The current most powerful nuclear device in the world is the Tsar with a payload of 210 Peta joules of energy or 210,000,000,000,000,000 joules
This means that The Tsar has only .00005% the power of a single MAC shot and that a single Mac shot at the ground would have the power of 20,000 Tsar Bombs! One Tsar Bomb has 2,800 times the power dropped on Nagasaki and Hiroshima.
To Further this: The Cairo Orbital Defence Platform shoots 3000kilo slugs at 149,000 kilometers per second. This is about 33.2 Zeta Joules.
This means a single shot from the Cairo is the equivalent of all nuclear Tests in history times 15,873.
I'm am pretty sure that my math is correct after rechecking it due to these large numbers.