Page 78 - CT&AI_CLasa_7_Part_1
P. 78
Which thermometer records a higher (d) Kabir, hot air rises in a column
temperature after two minutes, and why well above the flame, convection
does position within the liquid make such a currents push against the angled
large difference? (Algorithmic Thinking)
spiral surfaces causing rotation
(a) Fig (a), the bulb is closer to the heat even without flame contact.
source at the bottom. 8. On a hot summer day, the temperature
5 km away from the sea is 38°C, while at the
(b) Fig (b), hot water rises by nearby beach it is only 30°C. What is the most
convection and accumulates at appropriate explanation for this temperature
the top, the upper thermometer difference? (Abstract Thinking)
records higher temperature even (a) A sea breeze brings cooler air from
though it is farther from the flame. the sea to the land, lowering the
coastal temperature.
(c) Both record the same
temperature, water conducts heat (b) The region away from the sea
equally in all directions. contains more water, so it heats
up faster than the coast.
(d) Fig (b), hot water sinks and collects
at the bottom. (c) Sand at the beach reflects most
7. A paper spiral is cut and of the Sun’s heat back into space,
suspended above a burning keeping it cooler.
candle as shown in the figure.
Within seconds it begins (d) A land breeze during the day
to rotate. Meera says: 'The carries cool air from land to the
candle's flame physically
touches the paper and pushes sea, cooling the beach.
it.' Kabir says: 'The spiral 9. A brand of "Smart Windows" uses two layers
rotates because of convection of glass with the air sucked out from the
currents , rising hot air pushes middle to create a vacuum. How would these
against the angled surfaces of
the spiral.' After observation, windows help a homeowner in a very hot
the spiral rotates even when held 15 cm climate? (Decomposition)
above the flame , far too high for direct flame
contact.
Which student is correct, and what does the
fact that rotation occurs 15 cm above the
flame specifically prove? (Decomposition)
(a) Meera, the flame must be touching
the paper at 15 cm because flames
are invisible at that height.
(a) They would prevent the sun's light
(b) Kabir is right but only when the
spiral is within 5 cm of the flame. from entering the house.
(c) Both are wrong, the spiral rotates (b) They would block heat from the
due to static electricity from the outside air from entering via
candle. conduction and convection.
76 Computational Thinking-7 (Science)
