Lava Cooling

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What is lava?

        Lava, it's hot, it's colorful, and it comes out of the earth. However, where does it come from? What is it?
        These are all really great questions. Lava is molten rock that is heated beneath the surface of the earth through friction and the subduction of the Earth's crust. While lava is beneath the surface of the earth, it's referred to as Magma, but it principle it's the same material. Lava takes on the properties of the rocks that are melted down. This means that lava in areas like Hawaii tends to be runny and less viscious. While lava from Washington will be more viscious and thick.
        The type of eruptions also vary by area since the intensity of the eruption will largely be related to the composition of the lava. Which is why Mt. St. Helens eruption in 1980 was a deadly eruption, and why eruptions in Hawaii tend to be calmer.
        There are also different types of lava flows, which again, are mostly based on the composition of the lava. One such example is a rhyolite lava flow. examples of different type of lava flows can be found here:

http://www.geology.sdsu.edu/how_volcanoes_work/andesiterhyolite_lava.html

The Physics of Cooling Lava

        Physics actually explains what happens during cooling in a few different ways, one of which is the conservation of energy. Heat is considered a form of energy that is either gained or loss through different processes. One such process that most people are familiar with is friction.
        The conservation of energy simply states that energy is not able to be created or destroyed. In terms of lava this heat is transfered to anything that comes into contact with the lava, from the air, ground, water, and hopefully not your home or you. This can actually visibly be seen when lava is in contact with water, since the water is being to heat up and turn into steam. It can also be seen when it catches a tree on fire.
        Newton's Law of cooling describes how heat is transferred between enviornments. The following equation is what models Newton's Law of Cooling:

The University of British Colombia describes the equation in the following way:

Newton's Law of Cooling states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature (i.e. the temperature of its surroundings). Newton's Law makes a statement about an instantaneous rate of change of the temperature. We will see that when we translate this verbal statement into a differential equation, we arrive at a differential equation. The solution to this equation will then be a function that tracks the complete record of the temperature over time.

~The University of British Colombia

The equation for Newton's Law of Cooling is really useful in determining how something will cooldown overtime. However, it is important to remember that just because something is cooling down, does not mean that energy is being loss. In the context of just the lava the energy is being lost, but when considering the surrounding, energy is simply being transferred.