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Page 78 - CT&AI_CLasa_7_Part_1
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    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)

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