Expansion solid

1. Apperception
•Why is a space
left between the
railway line
where one
piece joins the
next?

2. Thermal Expansion
Objective
Investigating thermal expansion
in solid

3. Activity
Using your Student Worksheet 11.6Using your Student Worksheet 11.6
(page 129)(page 129)
Do the experiment in your groupDo the experiment in your group

4. Summary
•Solid expand when they are heated, and
decrease in volume when they get colder.
•From a microscopic point of view, the result
of heating a material can be explained as
follows:
–There is an addition of energy to the material
–The internal energy of the atoms of the material
increase, causing atoms to vibrate
–The vibrating atoms now occupy more space
when hot compared to when cold.

6. Thermal
Expansion
Expansion
of solid
Expansion
of liquid
Expansion
of gas
Linear
expansion
Area
expansion
Volume
expansion
Dl= lo. a. Dt DA= Ao. b. Dt DV= Vo. g. Dt

7. Linear Expansion
l
o
Dl
l
t

8. Linear Expansion
•The magnitude of the thermal
expansion of the solid depend on :
–Type of solid
–Temperature rise
–Length

9. Linear Expansion
•The expansion of solid body is
proportional to the temperature rise
and to its length
We can make Formula
Dl ~ l
o
D
t

10. Summary
Or We can write in equation of thermal
expansion:
Dl = a l
o
D
t
Dl = change in length (m)
a = coefficient of thermal expansion (
o
C
1
)
l
o
= Initial length (m)
D
t = change in temperature (
o
C)

11. Summary
•On a hot day, the metal expands and
if it were not allowed to do this, the rails
would bend out of shape.
•This has caused railway accident in
the past.
click

12. Area Expansion
A
o
DA
A
t

13. Area Expansion
We can make Formula
DA ~ A
o
D
t

14. Summary
Or We can write in equation of thermal
expansion:
DA = b A
o
D
t
DA = change in Area (m
2
)
b = coefficient of thermal expansion (
o
C
1
)
A
o
= Initial Area (m
2
)
D
t = change in temperature (
o
C)
click

15. Volume Expansion
V
o
DV
V
t

16. Volume Expansion
We can make Formula
DV ~ V
o
D
t

17. Summary
Or We can write in equation of thermal
expansion:
DV = g V
o
D
t
DV = change in Volume (m
3
)
g = coefficient of thermal expansion (
o
C
1
)
V
o
= Initial Volume (m
3
)
D
t
= change in temperature (
o
C)