“Why don’t we nuke them?” – Donald J. Trump, in reference to hurricanes [allegedly].

It was this moment, when this [alleged] suggestion from the President of the United States of America began circulating the internet, and an unprecedented wave of elation struck the science precinct. It was here: the moment of reckoning for each and every graduate of Paul Francis’ PHYS1101 course. All of these years of training, of hard work, of approximating pi = 1 had prepared us for this exact situation. So, can a nuclear bomb stop a hurricane and how is it that all of your first-year friends, who have never even completed a tax return, can tell you with such confidence?

Ninja physics is the practice of simplifying complicated situations to achieve a quick and approximate solution. The purpose of this technique is to arrive at a ballpark answer to get a rough idea of what the result will be and thus, if more accurate calculations are even needed. Firstly, the key facts of the problem are gathered and any irrelevant information is discarded. Then, complicated numbers are approximated to the nearest integer (whole number) or nearest order of magnitude (1, 10, 100 or 100, 000). For example, depending on how rough we want our approximation to be, we can have π = 3.14159 ≈ 3 or π = 3.14159 ≈ 1. From then, simple formulas – which you would probably recognise from Year 10 – 12 Science – are used to come to an approximate result. While it is unlikely that this is the type of physics that won Brian Schmidt his Nobel Prize, it is incredibly useful for fact-checking scientific claims in media, determining a starting point for measurements and plenty of other daily uses.

So, how would we use ninja physics to determine if a nuclear bomb can halt a cyclone?

Step 1: Gather our facts and discard irrelevant information

Firstly, we would need to find any relevant information and facts about the hurricane as well as a nuclear bomb. We know that hurricanes are fuelled by energy released when water vapour condenses into liquid water, with the energy produced termed the latent heat of condensation. This energy released causes huge amounts of air to heat and rise higher into the atmosphere, where it cools and promptly descends again. In the same way that water circles a sink drain, the rotation of the Earth causes the air currents to twist in a phenomenon known as the Coriolis effect. This leads to incredibly fast circular winds that reach speeds of hundreds of kilometres per hour – several times faster than cars on a highway! Data we might try to gather would include the size of the storm system, wind speeds, density of air and water within the hurricane, as well as energy produced by water condensing. For the nuclear bomb, we need to find the energy released upon explosion so that we can compare the energies and predict the effect.

Step 2: Approximate and calculate

The next step is to determine how to make this information at all useful for us through simple calculations and approximations. At the end, we need to be able to compare the nuclear explosion to the hurricane in some terms, so calculating the energy within each system would be useful. For the hurricane, this can be done in many different ways – here are two of the main methods:

Option 1: Calculating the kinetic energy (EK) of the air caused by the wind movements
Knowing data on the wind speeds and the size of the hurricane, we could approximate the average velocity of air (v) and the total mass of air (m) within the system. We could then use EK = 12mv2 to approximate the total energy of the hurricane!

Option 2: Find the total energy produced by the latent heat of condensation in the storm
Knowing the energy produced when one kilogram of water vapour condenses and the density of water within the hurricane, we can approximate the total energy.

Once we use either of these methods, we’ll end up with a quantity in joules, which is the main unit of energy. We can then compare this to the energy released in a nuclear explosion, which can be found online!