Temperature and Heat

Activities

Activity 1
Questions

This activity consists of two groups of questions. The first group of questions can be used to develop a short student discussion before viewing each part of the video. The second group of questions can be used in discussion or as a written task after part or all of the video. Either group of questions could be used for homework tasks.

Before Viewing

Question 1

How can you see in the dark?

What do a television remote control and a burglar alarm have in common?

How can a police helicopter follow an escaping car thief in the dark?

What would the world look like if you could see the temperature of things?

Describe your kitchen, high street, or body, using colour codes for different temperatures.

Question 2

How does our sense of temperature work?

How warm do you feel? Why do we disagree about how warm it is? Are you a warm person or a cold person?

Why does the bed feel warm when you get up, but cold when you go to bed?

What (apart from the weather )makes you feel cold or hot?

You see with your eyes – but where is your sense of temperature most accurate?

Question 3

How does a thermometer work?

What is the difference between degrees Celsius and Fahrenheit?

How many different thermometers have you used, and what do they measure? (You might not be able to see the thermometer, but only the result of the measurement.)

Question 4

How do things warm up and cool down?

Why does a hot cup of tea cool down and why does a cold ice cream warm up?

When does a cup of tea stop cooling down?

How could you turn a mixture of cream, sugar and fruit into ice cream?

Which has more heat, an iceberg or a cup of tea?

Which is warmer, an iceberg or a cup of tea?

After Viewing

Question 1

Draw a coloured sketch of your kitchen as seen through a thermal-imaging camera.

Question 2

Some people lose their sense of temperature after a stroke.

(a) Make a list of dangerous situations for these people.

(b) What precautions could be taken to avoid these dangers?

When you run a bath you have to mix the cold and hot water.

(c) How do you check the temperature?

(d) Why does it help to use a different part of your body if you have to check a second time?

(e) What changes does your body go through if your bath is rather hot?

Question 3

(a) Using a thermometer is not as easy as it seems. Write a set of instructions that will help students to measure the temperature of tap water accurately.

(b) The red spirit in a laboratory thermometer expands when it gets warmer. Imagine that you could see the particles of spirit. Draw a picture to show what the particles would be like when the spirit is cool and when it is warm. In your pictures show how far apart the particles are and how fast they are moving.

(c) You can make a thermometer with a small glass bottle, a cork, some Blu-Tack, a transparent straw, a piece of paper and some ink. Sketch a design and explain how your thermometer works.

Question 4

If a hill walker is lost in cold weather and suffers from exposure, their body temperature can fall below the normal level. One treatment is to give the walker a bath in warm water.

(a) Use the particle theory to explain how this would work.

(b) Why is warm water used instead of warm air?

Activity 2
Hot stuff

This activity prompts students to consider the advantages of using a data logger to collect experimental data. They then go on to plan an experiment making use of a data logger. If appropriate data loggers are available, the teacher may wish to allow the students to carry out their investigation.

A data logger is a device that can store measurements made by an electronic sensor. At least three sensors can be connected to most data loggers. The information in the data logger can be downloaded into a computer. The results can then be analysed and graphs can be drawn using computer software. Data loggers can record temperature measurements every tenth of a second and can continue recording data automatically, sometimes for days. For outdoor experiments, the data logger will work even when not connected to the computer, and can run on batteries. Most temperature sensors have an accuracy of 0.1^oC.

In your group, discuss the advantages and disadvantages of working with a data logger instead of a thermometer and stopwatch. Make a table of your ideas. Try to think of as many advantages and disadvantages of data loggers as you can.

Plan an investigation using a data logger to find out what happens to the temperature in one of the following cases:

• An ice cream is left out of the freezer.
• A hot cup of tea starts to cool.
• The fridge door is opened and closed.
• The central heating goes off at night and on in the morning.

When you use a data logger you have to decide the total time that your experiment will last, and the frequency of measurements. Usually, the longer the experiment, the less frequent the measurements.

1. How long will your experiment last? How frequent will the measurements be?

2. Where will you position your data logger and what power supply will you use?

3. How many sensors will you use and where will you put them?

Data loggers can produce a very large number of measurements. You might have to edit the measurements in a spreadsheet.

4. How will you present your data? What software can you use to do this? What type of graph should you draw?

Produce a report of your experiment using a DTP program. Include your data and graphs.

Activity 3
Safe to drink?

In this activity students are asked to select from a variety of modern technologies to design a mug that will give off high-temperature warnings for people who have lost their sense of temperature.

Some people have no temperature sense: the part of their brain that receives signals from their skin has been damaged by a stroke. For these people, drinking a cup of coffee can be very dangerous.

The following new techniques and materials have made it possible to design a safer mug:

• A range of temperature-sensitive dyes which change colour according to the temperature.
• Tiny electronic thermistors that can sense temperature very accurately and produce an electronic signal.
• Tiny microprocessors that can receive information, process it and send it to a display.
• Thin liquid-crystal displays that can be built into any manufactured object to display information.

Design a mug that will:

give information about the temperature of the drink it contains

protect the user from accidentally touching very hot drinks

Write notes on your design to explain how each part works and how the parts are connected.