How to determine the cooling rate of drinks in mugs?
- How much variation is there in how long containers keep drinks warm for?
- How much effect does a lid have?
- Do drinks take the same time to cool from 60 to 50 °C as from 50 to 40 °C?
- What does this experiment have to do with reducing the impact of heating houses upon climate change?
Estimated time: depends on drinks containers – Mostly 30 minutes though some can take hours. No prior knowledge needed.
Equipment required
- Hot drinks containers. Ideally including an identical pair – one with a lid
- Measuring jug
- Thermometer that works up to 100 °C
- A clock or timer
- Paper to record results in a table
Risks
- Hot water can scald, take extreme care
- Take care if handling a glass thermometer
- mop up spilt water immediately
How to
Watch the video, then follow the instructions.
- List your drinks containers in a results table (as in video). Download table here.
- Very carefully use the measuring jug to put 100 ml of boiled water into each container. If the water temperature in the container is less than 60 °C, empty and refill with new hot water. Put on any lids.
- Measure room temperature.
- Measure water temperature for each container about once a minute. Record the time when the temperature is 60 °C. Replace lids each time and don’t leave the thermometer in the container.
- Continue measuring water temperature about once a minute. Write down the time when the temperature is 50 °C.
- Continue measure water temperature and write down the time when the temperature is 40 °C. Give the thermometer time to settle outside the water, then measuring the room temperature.
- Calculate times each drinks container takes to cool from 60 °C to 50 °C and from 50 °C to 40 °C, and record values.
- Share your results with us using the form below on this webpage.
Thoughts, tips and information
SI measurement units
- Second (s) for time (and minute = 60 seconds)
- Kelvin (K) for temperature
- Metre (m) as litre for volume m3
Challenge topics
Climate measurement, measurement science, thermal properties, insulation, maths
- Which material keeps drinks hot best?
- How do lids affect the result?
- What is the coldest temperature the drink will ever reach?