INTERESTING FACTS: EVERYDAY SCIENCE. Q. Ice packed is saw dust does not melt quickly. Why ? Ans. Saw dust is a bad conductor of heat and protects the ice from the external heat and hence from melting away quickly. Q. What is an electric fuse ? What purpose does it serve ? Ans. A thin wire used in maintaining the condition of the energy; it prevents overloading of energy. Q. A plane approaching at a speed of 1000 m.p.h. is not heard. Why ? Ans. Sound travels at a speed of 760 m.p.h., hence a plane approaching at a speed of 1000 m.p.h. cannot be heard. Q. Why do the stars twinkle ? Ans. The stars seem to twinkle due to two causes. First the lightfrom the stars passes through several mediums; secondly our vision has a tendency to distract. Q. Why does water get cooled in an earthen pitcher ? Ans. Pitchers have pores through which water percolates which evaporates. During evaporation heat is taken away and the watergets cooled. Q. Glass when heated cracks while metal does not. Ans. Glass being bad conductor of heat only that part is heated which comes into contact with heat while the other parts remainunaffected. This results in unequal expansion and hence the tension which cracks the glass. On the other hand, metal is a good conductor of heat and so allits bulk gets uniformly heated and hence no surface tension.
Posted on: Thu, 04 Jul 2013 07:32:16 +0000
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