Step 1: Find the Size of the Explosion
First, you have to find the exact page, or scene where an explosion is shown as a feat. Depending on the environment where the explosion occurred, you may have to scale the size of a smaller object that is shown in the map. Let's do an example...
Example 1: An Explosion Occurs
An explosion of unknown size occurs in this picture, engulfing the object. Find the size of the explosion. The explosion is shown in the below scene.
- The first thing that notice is that you do not know the exact size of the object shown in the picture.
- However, you are allowed to find the size of the object by comparing it with an another object, such as the one shown beside the object.
Step 2: Finding the Radius of the Explosion
From example 1, there is a scene that shows the object in relation to the object shown from the first picture. This is located below. We will use the height of the door as a reference in this case.
- Given that the door size of the door is 7 feet, or 2.13 metres tall, you can now find the size of the object.
- Log down the size of the object.
- After you have found the size of the object, you compare the size of the object to the diameter of the explosion shown in the first picture.
- Divide the diameter by two to get the radius of the explosion.
Step 3: Finding the Yield of said Explosion
Here is a sample calculator that you can use in order to find the yield of an explosion, provided that you have found the exact diameter of it.
- Generally, you take the near-total fatalities section from the list of calculated values/calculator above.
- As for why it is used, the definition of near-total fatalities means states that: all large above-ground structures are destroyed within that radius, as well as causing 100% fatalities to anyone that is affected within the radius due to sheer pressure alone.
- When you get the result of said explosion, you multiply the value by 0.5. This is because only 40 to 50 percent of the total energy of the explosion is actually from the blast.
- Keep in mind that if the explosion is an actual nuclear explosion, you can disregard the point above.
If you are having a hard time using the nuclear calculator, this equation can be used to find the yield of said explosion.
- Air blast radius (near-total fatalities) Yield: Y = ((x/0.28)^3)/1000
Misc 1: Somebody Tanks an Explosion!
Let's say an explosion occurs in front of a character, and said character takes the explosion at close proximity. To find the actual amount of the energy from the explosion that he/she
- First, the energy radiating from explosion only makes contact with the front of the body, and not the back as well.
- Second, the surface area of the person making contact with the explosion must be calculated.
- Here is a calculator you can use to find the surface area of a person. Just make sure to multiply the final result by 0.5 (divide the final result by 2) at the end.
Misc 2: The Inverse Square Law
- Applies when a energy is directed outwards from the center in a 3-Dimensional space.
- The intensity of said energy decreases proportionally as the energy is directed further away from the source.
As for how this relates to explosions?
- This means that further you are away from an explosion, the less damage you will take from it.
- Power of said explosion is distributed over a larger and larger surface area as the distance from the epicenter increases.
- The surface area of a sphere is A = 4πr^2. This is relevant because when an explosion occurs, the energy of said explosion radiates outwards as a sphere.
- The intensity of said explosion at a distance of r is I = P/4πr^2, where I = Joules of energy.
- P = Power/Yield of explosion, in Tons of TNT
Let's do an example.
If an explosion of 7 kilotons of TNT occurs, find the intensity of the explosion at 300 metres away from the epicentre.
- First, we set P = 7000 Tons of TNT, as that is the yield of said explosion
- Second, we set the radius, or r = 30m
- Third, we find the value of I, or the intensity of the explosion at a specific distance.
- I = (7000 Tons of TNT) / 4π(30m^2)
- This means at 30 metres away from the epicenter of the explosion, the shockwave is hitting with a force of I = 0.619 Tons of TNT.