THERMAL EXPANSION 229
Assignment 6
This assignment covers the material con-
tained in chapters 19 and 20.
The marks for each question are shown
in brackets at the end of each question.
- A block of aluminium having a mass of
20 kg cools from a temperature of 250°C
to 80°C. How much energy is lost by
the aluminium? Assume the specific heat
capacity of aluminium is 950 J/(kg°C).
(5)
- Calculate the heat energy required to
convert completely 12 kg of water at
30 °C to superheated steam at 100°C.
Assume that the specific heat capacity of
water is 4200 J/(kg°C), and the specific
latent heat of vaporisation of water is
2260 kJ/(kg°C).(7)
- A copper overhead transmission line has
a length of 60 m between its supports at
15 °C. Calculate its length at 40°C, if the
coefficient of linear expansion of copper
is 17× 10 −^6 K−^1 .(6)
- A gold sphere has a diameter of 40 mm at
a temperature of 285 K. If the temperature
of the sphere is raised to 785 K, determine
theincreasein
(a) the diameter
(b) the surface area
(c) the volume of the sphere.
Assume the coefficient of linear expan-
sion for gold is 14× 10 −^6 K−^1. (12)
