Thermos Lab Report

1312 Words 6 Pages
Aim:
The aim of this practical experiment is to design, construct and test a container to insulate a cup of hot water, preventing and minimizing heat loss via the mechanisms of conduction, convection and radiation. The thermos design must be freestanding and effective against any means of heat loss to the surroundings. This data is then compared to a control, which is a cup of hot water in a polystyrene cup without any sort of insulation and protection against heat transfer to determine the effectiveness of the thermos in regards to heat loss via conduction, convection and radiation.
Background Physics:
Conduction: Transfer of heat through a substance as a result of collision between neighbouring vibrating particles, usually in solids, metals
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8) Empty cups, cool temperature probes in cold water until it reaches room temperature.
9) Repeat steps 1-8 for second trial.
Our thermos was constructed with materials that minimizes energy loss by conduction, convection and radiation to the greatest degree. We created the thermos with multiple layers, starting with the two polystyrene cups in the centre, which were wrapped in bubble wrap and taped. A polystyrene lid was also cut out and placed on top of the inner polystyrene cup. Each layer of polystyrene and paper cups were wrapped in aluminium foil. We also, covered the outside and bottom of the thermos with polystyrene and aluminium foil. Finally, we covered the hole in which the heat probe was inserted with sticky tape. Throughout the construction of the thermos, we tried to imitate the mechanisms used in a commercial thermos to reduce heat
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This is effective as polystyrene is an insulator and can block transfer of heat energy towards the surroundings. We also incorporated bubble wrap into our thermos design to try and imitate the effect of the double glass layer in a commercial thermoses. The air trapped in the bubble wrap is extremely effective in keeping heat inside and reducing heat loss as not only does the heat have to go through plastic (which is a very good insulator) but it also has to pass through a layer of air/vacuum. This prevents conduction from occurring throughout most of the thermos as conduction can only occur near the top of the thermos where the layers meet. The almost nonexistence spaces of air created by all the tightly bound layers results in almost no transfer of heat from the wall containing the hot water to the outer wall by convection. The polystyrene lid is also used in order to prevent heat loss via convection as hot air rises to the top, carrying energy with it. The aluminium foil in each layer, prevents heat loss by radiation as it reflects radiated heat back to the inside, the same way a space blanket

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