Page 60 - SP015 Past Years PSPM Chapter 6 -14 Ver 2020

PHYSICS PSPM SEM 1 1999 - 2017

PSPM 2002/2003 SF017/2 No. 7

6.

X Y
Q Cold
Hot P

FIGURE 12.2

A metal bar XY contains a part of other metal PQ as shown in FIGURE 12.2. Sketch
temperature versus length graph for the bar if it is

(a) insulated. [2 m]

(b) not insulated. [2 m]

PSPM JUN 1999/2000 SF015/2 No. 6(b) Edited

3
7. A water tank of measurement 2  2  1 m is filled up at temperature 96 C. The tank is
1 cm thick. Calculate the rate of heat loss through conductivity on each wall of the tank
if the temperature outside the tank is 22 C. Given thermal conductivity of the tank is
-1
-2
-1
3.78  10 W m K . [4 m]

PSPM JUN 2000/2002 SF015/2 No. 13(b)

2
8. A cylindrical container with a cross-sectional area of 2.0 m and its bottom made from
2.0 cm thick iron contains water at temperature 100 C. This cylinder is then placed on
a heater where 1 kg of water is evaporated every 5 minutes.

6
-1
(a) If latent heat of vaporization L = 2.26  10 J kg , calculate the heat provided to
the water in 1 second. [3 m]

-1
-1
-1
(b) If thermal conductivity of iron is given as 50.2 J s m K , what is the
temperature at the bottom surface of the cylinder that touches the heater? [3 m]

PSPM 2004/2005 SF017/2 No. 7

2
9. A slab of thermal insulator has cross-sectional area 200 cm and thickness 5.0 cm. Its
-1
-1
thermal conductivity is 0.2 W m C . If the temperature difference between opposite
surfaces is 75 C, what is the total heat flow through the slab in 1 hour? [3 m]

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