Mpemba Effect – Hot Water Freezes Faster Than Cold Water

By Anupum Pant

In the past, we have seen that when it comes to estimating temperature, we are not so smart. Once again seeing the Mpemba Effect defying all known logic, reminds me to be careful about applying logic to most of the natural phenomena which are seemingly simple but in reality are extremely complicated.

By applying simple logic, a 7-year-old could tell you that cold water should turn into ice quicker than hot water would. It should, because a hot liquid contains a lot more heat as compared to a colder liquid, which [the heat]  has to be removed in order to freeze it. Yes, it is what anyone who is unaware of the Mpemba Effect would think. But, that isn’t the case with water. It turns out that a very common substance – water – is not as simple as it looks.

Mpemba Effect

Since the time of Aristotle and Descartes, scientists have noted that hot water can freeze faster than cold water (and yet the effect is not popularly known among us today). Although the effect was noted back then, the actual mechanism which caused it remained a mystery all along…until the year 2013.

All this time this effect must have been known by some other term because, it was not until the 1960s it was named “Mpemba effect”. It was named that after a Tanzanian cookery student Erasto Mpemba when he observed that hot ice cream mix froze faster than the cold mix.

Several theories have tried to explain the mechanisms that cause the Mpemba Effect. Not even one of them was convincing enough. Probably this is what propelled the geniuses from Singapore who could finally solve this mystery during the month of October this year.

What causes it?

In simple words, Hydrogen bonds cause this effect – faster freezing hot water. Normally, individual water molecules are connected by this bond called the Hydrogen bond. Think of the water molecule as a string with two bullies – hydrogen bonds – one on either side. These Hydrogen bonds pull this string from both sides. As a result, the string stretches. We’ve all fought with rubber bands and know that a stretched string has a butt load of energy stored inside it. The same thing happens with water. Energy is stored in stretched water molecules at normal temperature. This extra energy has to be removed to cool water.

At a higher temperature, the heat kind of weakens these bullies. So, the weak bullies aren’t able to pull the string as much. Now, individual molecules sit apart. They are no longer stretched. Thus, not much energy is stored in these strings anymore. They have given up energy. There is no longer any extra energy that needs to be removed. Hence, cooling is faster.

Sorry: Today I don’t have my buddy – the internet – with me. So, you won’t see any outgoing reference links today. I have a just a bit of internet (a slower 2G connection) which I’m using up to publish this.

Drones beyond Amazon’s Drone Delivery System

By Anupum Pant

For a long time I’ve had this idea noted in a file and the hottest news from Amazon, linked to a “revolutionary drone accomplishment”, pushed me into writing it down. Since I cover topics ranging from a gamut of areas in the name of science, I thought, through this article, it would be appropriate for me to enable my readers see beyond an ongoing viral news topic – The unveiling of Amazon’s drone delivery. If you haven’t seen it already, you’ll find the video here. [Video] [details here]

Long before Amazon released its concept of Premier Air, 30 minute delivery, the idea – usage of drones for things you wouldn’t have thought of – has been tested or put to use in several related ways. Some of the reported tests and uses of drones are as follows:

Drones for food delivery: During June 2013, with an idea (read: PR stunt) that would inspire Amazon in the future, Dominos U.K. released a test video of the “DomiCopter”. In the video they showed an unmanned drone picking up a Pizza and delivering it to the customer without having to encounter any traffic in between. Slick! But, that isn’t all.
A year before this, Taco delivering drones as well as a Burrito bomber drones were also seen. All of them had gone viral. Yet, we still have a long way to go to see these delivery systems working legally.

Mosquito killers: A North Florida-based company that supplies drones for military missions, showed a drone that would speed up detection of stagnant water. As a result, helping the authorities cut mosquito breeding grounds in Florida.

Hover Cameras: Golf channel tested a new way of filming golf tournaments using drones this year. Besides that, we’ve seen drones being used for sports photography and journalism too.

Drone Waiters: To promote a new product, YO! Sushi, a London restaurant started using ‘flying trays’ for bringing burgers to their customers. These flying trays were nothing but drones carrying food trays. Also, it increased their speed ‘exponentially’.

Drone Constructors: This project dates back to the year 2010-11. Two architects, Garamazio and Kohler demonstrated aerial construction using unmanned drones. However, they demonstrated building process for a heavily scaled down version of a building using foam bricks. Nevertheless, it was an achievement in the year 2011, when QuadroCopters were just starting to get popular.

Although we have seen a lot of unusual uses for drones being demonstrated all around the globe (many more creative uses remain to be seen), we are yet to see their practical implementation; especially for projects like the Amazon drone delivery, which require drones to move around in a complicated airspace (in terms aviation rules).

Federal Aviation Administration (FAA) is actively working on rules for unmanned aerial vehicles. Still we won’t see drones moving around legally and freely, any time before 2015.

Everything else you’d want to know about drones: PopSci