Supporting the teaching of Earth sciences at all levels
Experiment: Mike Tuke              Realised by: Julian & Phillipa Priddle                  Sponsor: PESGB



The purpose of these activities is to determine what factors control the speed of cooling of an igneous body. Lava lake, Hawaii, copyright USGS

Background science

There are three mechanisms by which heat is transmitted. Heat is transmitted by conduction, for example, from an intrusion to the surrounding rock.  If there is water in the surrounding some heat will be transmitted by convection.  Lavas lose heat to the air by radiation. The speed of cooling of a block of hot material depends on two major aspects: the amount of heat energy in the material and the speed that the heat can be transferred to the cooler surrounding material.   The amount of heat energy is determined firstly by the size of the hot block, and secondly by the specific heat capacity of the material of which the block is composed.  Some materials are able to hold more heat per unit mass than others, for example, aluminium holds twice as much heat as the same mass of steel.  The speed of transfer of the heat energy is dependent on three things: 1. The temperature difference between the hot material and its surroundings.  The greater the difference in temperature, the faster the transfer of heat energy.  2. The thermal conductance of the hot material. Some materials can transmit heat energy faster that others, for instance, a metal mug of tea feels hotter than a china mug because metal has a higher thermal conductance.  If the surrounding material is solid its thermal conductance is also important. 3. The surface area of the hot material. The greater the surface area, the faster it will lose its heat energy. There are five separate virtual activities.

1 Size. 

This activity is based on cooling aluminium cylinders of varying sizes and weights

2 Surface area.

This activity looks at cooling aluminium cylinders all the same weight and volume but with varying lengths and diameters.

3 Grain size

This activity is based on cooling cubic blocks all the same size and composition but with different grain sizes; gabbro, dolerite and basalt.

4 Composition

This activity looks at cooling cubic blocks all the same size but with different compositions; granite and gabbro.

5 Water in surrounding country rock

In this activity two identical soft drinks cans, one in dry sand and the other in damp sand are filled with boiling water.
Instructions for experiment 1 Instructions for experiment 2 Instructions for experiment 3 Instructions for experiment 4 Instructions for experiment 5 virtual experiment 1 virtual experiment 2 virtual experiment 3 virtual experiment 4 virtual experiment 5