THERMAL PHYSICS 1 - Exercise
Thermal Expansion
1. The length of an aluminum rod at 20 °C is 4 m. If the linear coefficient of the aluminum is
0,000024/°C, then what is the length of the aluminum at 100 °C?
2. A 20m copper with CTE 0,000017/°C is heated in the metal oven from -20°C until it reaches 220°C
Calculate the expansion length of copper ?
3. The length of metal at 50°C is 50,03 cm. If the length of the metal at 20°C is 50 cm then what is the
linear coefficient of the metal?
4. An aluminum wing with CTE 23 x 10-6/°C on a passenger jet is 36m long when its temperature is 29
degrees Celsius, at what temperature would the wing be 2cm (0.02 m ) shorter?
K:
CTE= 0,000023
Lo = 36m
T awal = 29
change L = 0,02m
w: T
A:
delta T = change L : (Lo x CTE) = 24oC
at temp: 29-24 = 5oC
5. (Prove your answer using formula)
A metal bar is heated and its length is expanded by x cm.
a. How much will the expansion be, if the temperature increment is tripled?
b. How much the expansion will be, if the temperature increment is doubled and the original
length is halved?
6. Two metal bars (A and B) have the same initial length which is 5m, but they are made from
different materials. They are heated until they have the same temperature change.
Metal A has CTE two times bigger than metal B. if the expansion of metal A is 1 cm, determine:
a. The expansion of metal B? 0,5cm
b. Final length of metal A!
c. Final length of metal B!
d. Final length of metal A if it is cooled instead of heated, using the same temperature
change!
e. Final length of metal B if it is cooled instead of heated, using the same temperature
change!
7. Several metals with the same material and same length (at its initial temperature) are heated.
Below is the measurement data:
Metal
Initial temperature
Temperature after Heated
A
10oC
45oC
B
80oC
90oC
C
50oC
70oC
1
D
75oC
95oC
a. Which metal get same amount of expansion?
b. The metal B final temperature is bigger than metal A, is this means metal B expand more
than A?
c. If metal B expand 0,5 cm, how much metal C will expand?
8. Why the lid of jar will be easier to open if
it is dipped into hot water?
9. What will happen if the entire jar
including the body of jar is dipped into
hot water? Will it still easier to open?
10. Two pieces of railroads in Jakarta made of low alloy
steel (CTE=16⋅10−6/°C) will be joined together. If the standard
length of each railroad is 30 m, how big should the gap be?
Explain your answer! (find out max and min temperatures
in Jakarta) delta T= 8oC
Lo. CTE. delta T
30. 0,000016.8=...
GAP= delta L x 2
11. According to this picture, which materials from this table are possible to be the unknown metal?
Table 1
Material
Linear CTE(α)
x 10-6/°C
Iron
12
Lead
48
Limestone
8
Lithium
46
Magnesium
25
Manganese
24
Why did you answer that?
2
Density and Thermal Expansion
12. State the formula of density!
13. Explain the effect of thermal expansion to density of object!
14. Will solid iron float or sink in liquid iron? Explain using the concept of density!
15. Why do smokes always go upward?
3