# To investigate the rate of cooling in three different types of cups

## Problem

The problem for this experiment is to investigate the rate of cooling in three different types of cups. They will be used as typical coffee cups for commercial purposes. The cups a polystyrene cup, a paper cup and a plastic cup.

Water has a high specific heat capacity. This makes it a very useful material for storing and carrying heat energy. Its heat capacity is 4200 joules per kilogram per  °C (4200J/kg °C).

This is how water compares with other material:

Calculating heat energy:

For water:

4200 J heats 1 kg through 1 °C

8400 J heats 2 kg through 1 °C

84 000 J heats 2 kg through 10 °C

You could also calculate the result using an equation

heat energy = mass * specific heat * temperature

gained                         capacity              rise

(J)                (kg)         (J/kg °C)              (°C)

Heat tends to flow away from a hotter object to a cooler surroundings. Heat is mainly lost I conduction, convection, radiation and evaporation. For this experiment I will be only using convection, radiation, evaporation because conduction is mainly in solids.

## Convection

Convection mainly occurs in gasses and liquids gases and liquids are very poor conductors so convection is usually dominant process. When convection can’t occur, the heat transfer by conduction is very slow.

Convection only occurs when the more energetic particles move from hotter region to a cooler region and take their heat energy with them. Convection doesn’t happen in solids because there are no particles movement.