Nicole Ryan
The Rate of Heat Loss
Introduction
My investigation is to find out the main method at which a liquid cools. When a liquid cools down, it loses heat in four ways:
- Conduction
- Convection
- Evaporation
- Radiation
Aim
MY aim is to investigate which method of heat loss is mainly responsible for a cooling a liquid down by changing the main method of heat loss and measuring the cooling rate.
Prediction
Heat is generally transferred by conduction, convection, evaporation and radiation. All these processes can all happen simultaneously, but it is likely that one will give the greater heat exchange.
Below is a description of the processes that will affect my experiment.
Conduction
This is where heat energy passes through the walls of the can by making the particles of the can vibrate and then they will make the particles next to them vibrate causing the heat to pass through the walls of the can and out to the surroundings. Materials that are good thermal conductors tend to be good electrical conductors; metals such as gold, silver and copper have high thermal conductivity's and will conduct heat readily. Materials such as glass have much smaller heat transfer values and are poor heat conductors.
Convection
This is where the cooler water particles sink down to the bottom and the warmer water particles float up to the top. Convection will only affect my experiment if I did not have a lid. This is because the warm water will float up to the top and the heat energy will escape out of the top. If a pan of water was being heated from below then the water particles at the bottom of the pan will become warm as therefore become less dense, they will begin to rise to the top of the pan. As the warmer water particles begin to rise, the cooler water particles at the top of the pan will sink to the bottom, as they are less dense. Once at the bottom of the pan the will start to get warmer and become less dense. This process will continue until the pan of water is at the same temperature.
