1. unit 3
Heat and temperature.

2. Activities
1. Explain what happens when you put a potato boiled at
70 º C into a bowl of water at 10 º C.

3. Activities
2. Is it true that hot objects, like heaters, emit heat, and
cold objects, like ice, emit cold?

4. Activities
3. Compare the distribution of heat in the infrared photo.
For example: The hand is warmer than the flask. Use: -top
of the flask-water-hand-finger

5. Activities
4. What direction does heat flow in?

6. Activities
5. Why is mercury used in thermometers instead of
water?

7. Activities
6. Normal body temperature is 37 º C. Express this in º F
and K.

8. Activities
7. Copy and complete the text about heat.
Heat is _________energy which_______ from one
_________ to another. This transfer of _______is caused
by a __________ in temperature.
When a system ______heat, its __________ decreases.
When a system ________ heat, its ___________
increases.

9. Activities
8. Classify these phenomenas expansion or contraction.
Explain your reasons.
a.Why does a glass break when you add very hot water?
b.You remove a metal ring from your finger easily when
it is hot.

10. Activities
9. Explain why a solid changes to a liquid when it is
heated.

11. Activities
10. Look up the following words in a dictionary. Classify
them: heat loss or heat adsorption.
Condensation, desublimation, evaporation, melting,
sublimation, solidification.

12. Activities
11. How does heat transfers from a hot cup of
milk to our hands? What is this process called?

13. Activities
12. Explain how heat is transferred in each case:
a)Toast in a toaster
b)An element in an electric radiator
c)Soup boiling in a pan
d)Bread cooking inside an oven
e)A pancake in a frying pan

14. Activities
13. What would happen if you put
the inflated balloon in very hot
water immediately after taking it out
of the refrigerator? Try this
experiment, then describe and
interpret the results

15. Activities
14. A piece of iron heated to 150 º C is put
into a container filled with water at 25 º C.
a)What type of energy does the piece of
iron transfer to the water?
b)What type of heat transfer is taking place
between the iron and the water?
c)What process will occur after the iron has
been immersed in the water for a while?

16. Activities
15. Imagine the
temperature in New York is
22 º F. What kind of
clothing do people need to
wear?

17. Activities
16. The melting and boiling
point of ammonia are 195 K
and 240 K, respectively.
Express each temperature in
degrees Celsius.

18. Activities
17. Put the following temperatures
in order from highest to lowest:
a)22 º C
b)200 K
c)200 º F

19. Activities
18. Which of the following effects is
caused by heat?
a)The volume of a plastic ball
increasing when it is exposed to the
sun
b)An iceberg melting
c)Water evaporating from a glass
d)An aluminium spoon increasing in
length

20. Activities
19. Why is ice cream often available
in styrofoam containers?

21. Activities
20. Why do you think clothes dry
faster on an windy day?
Because wind…

22. Activities
21. Why are handles of fryinf pans
usually made of plastic or wood? Why is
the base made of metal?

23. Activities
22. Take ten ice cubes of approximately the same size. Wrap five ice
cubes in a woollen scarf. Leave the other five ice cubes on a plate.
Wait a few minutes. What happened?
a)Did all of the ice cubes melt?
b)Did it take the ice cubes the same amount of time to melt?
c)Did the woollen scarf heat the ice cubes?
d)Explain what has happened.

24. Activities
23. Two pieces of ice of the same size, at a
temperature of 17 º C are placed in two bowls.
One bowl is of metal and one is made of wood.
Which piece of ice melts first? Explain

25. Activities
24. Cut a spiral from a piece of paper. Attach a
thread and hang the spiral above a heater or a
lighted candle. Make sure the flame does not
touch the paper.
a)What do you observe?
b)How can you explain this?
c)What phenomenon has occurred?

26. Activities
25. Explain how heat is transferred in these
cases:
a)Opening the refrigerator door
b)A cup of soup cooling
c)When ironing with a steam iron
d)When a heater is on in a bedroom
e)When the light from a normal light bulb is on

27. Activities
26. Air is an insulator. Why do houses in cold areas have doubleglazed windows?

28. Activities
27. Investigate.
Compare the melting and boiling points of: helium, oxygen,
mercury and gold.