*Why does it not hurt when we cut our nails?

  • Nails are a part of body but have no connection with blood vessels and the nervous system. Hence, cutting them does not hurt us.


*Why are two blankets warmer than one which is double the thickness of each?

  • Two blankets are warmer because the air enclosed between the two does not allow that heat to go out.


*Why is it not safe to sleep under trees at night?

  • It is not safe to sleep under trees at night .Because the trees take in oxygen and give out carbon dioxide at night.


*How does soap make you clean?

  • When you mix soap with water, the soap and water spread out and make bubbles. Each bubble is a little balloon with air inside and a thin skin of soap and water outside. When you make lather, you are simply pumping air into the soapy water, blowing bubbles.

Just as a magnet is able to pick up iron fillings, soap bubbles also pick up dirt. They pull it away from our skin. Soapy lather has many bubbles in it. Each one can pick up a little dirt.


*How does a lie detector tell weather a person is lying or not during interrogation of suspected criminals by the people?


  • Whenever a person performs such actions as telling a lie, cheating and misguiding someone, his heart starts beating fast. During interrogation, by the police, the lie detector records the blood pressure, pulse rate and respiration of a person as he answers questions put to him. Since a person does not have voluntary control over these natural actions of the body they are likely to change if a person tells a lie deliberately. The lie dictating machine is called a polygraph and was invented in 1921 by a medical student.


*Why is brass used in statues?

  • Brass is an alloy of copper and zinc. It is used in making statues as brass is a hard metal and lasts long. It can be hammered, punched and molded into any shape without the danger of breaking it up.



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