RelativeResourceManager - MTX 221 2010 Chapter 4...

MTX 221 – 2010
Chapter 4 Recommended Problems
Some of these problems appear in the
7
th
Edition
of the prescribed textbook according
to the indicated numbers.
Some of these questions will be done in full
during the tutor session
Hoofstuk 4 Aanbeveelde Probleme
Hierdie probleme verskyn ook in die
7
e
uitgawe
van die voorgeskrewe handbook
volgens die aangeduide nommers.
Sekere van hierdie vrae sal volledig in die
oefenklas sessie gedoen word.
4.15 A piece of steel has a conductivity of k =
15 W/mK and a brick has k = 1 W/mK. How thick
a steel wall will provide the same insulation as a
10 cm thick brick?
4.15 ‘n Stuk staal het ‘n termiese geleiding van
k = 15 W/mK en baksteen het k = 1 W/mK. Hoe dik
moet ‘n staal muur wees om dieselfde insulasie as
‘n 10 cm baksteen te bied?
Answ / Antw: 1.5 m
4.17 On a chilly 10
º
C fall day a house, 20
º
C
inside, loses 6 kW by heat transfer. What transfer
happens on a 30
º
C warm summer day assuming
everything else is the same?
4.17 Op ‘n koue herfsdag van 10ºC verloor ‘n huis
met interne temperatuur van 20ºC 6 kW hitte.
Hoeveel hitte-oordrag is daar op ‘n 30ºC somers-
dag? Aanvaar dat alle ander fasette dieselfde bly.
Answ / Antw: 6 kW into the house / in die huis in.
4.34 Saturated water vapor at 200 kPa is in a
constant pressure piston cylinder. At this state
the piston is 0.1 m from the cylinder bottom and
cylinder area is 0.25 m 2 . The temperature is then