Page 61 - SP015 Past Years PSPM Chapter 6 -14 Ver 2020

PSPM SP015

PSPM 2005/2006 SF017/2 No. 7

10.

80 C M N 20 C

FIGURE 12.3

Two metallic rods M and N with similar length and cross-sectional area are joined
together and insulated. At steady state, the temperatures at their ends are shown in
FIGURE 12.3. The thermal conductivity of M is twice that of N. Calculate the
temperature at their adjoint end. [3 m]

PSPM 2007/2008 SF017/2 No. 7

11. How much heat flows through a sheet of copper 1.2 m × 0.8 m of thickness 3.0 mm for
1 hour if the temperatures of the surfaces are 30 C and 28 C respectively? (Given
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thermal conductivity of copper = 401 W m K .) [4 m]

PSPM 2011/2012 SF016/2 No. 8(b)

12. An insulated spherical glass bulb of radius 2.5 cm, thickness 0.4 mm whose outer
surface temperature is 30 C dissipates 55 W of heat.

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(a) Given the thermal conductivity of glass is 0.84 J s m C . Calculate the
temperature of the inner surface of the bulb. [3 m]

(b) Sketch a labelled temperature against distance graph of the heat conduction
through the bulb. [2 m]

PSPM 2013/2014 SF016/2 No. 8(b)(i)

2
13. Calculate the heat transferred in 24 hours through a 2.4 m metal sheet of thickness
1 cm when the temperature difference between the surfaces is 0.5 C. Given the thermal
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conductivity coefficient of the metal is 16 W m K . [2 m]

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