by Maria Vazquez
How does a thermometer work?
A thermometer contains alcohol, which expands when it get warm and contracts when it gets cool.
The thermometer reports the average kinetic energy of the particles in a substance. When the particles are hot are in contact with the alcohol in side the thermometer stem transfer kinetic energy to the alcohol particles. Soon all of the soon all of the alcohol particles are moving faster, pushing on each other more often and with more force. The distance between the particles increases, and the alcohol expands and its volume increases. Alcohol pushes stem of the thermometer. The greater the Kinetic energy the alcohol particles, the more the alcohol expands. Energy transfers to the alcohol until the average kinetic energy of the alcohol particles are the same as the average kinetic energy of the hot water.
When you put the thermometer into the cold water. The energy transfers from the outside of the glass thermometer stem to the water. Energy transfers from glass particles, lowering the kinetic energy of all the glass particles. When alcohol particles collide with lower energy glass particles, energy flows from the alcohol to the glass. The alcohol loses kinetic energy and contracts. When the average kinetic energy of the alcohol particles is the same as the average kinetic energy of the water particles.