Why so?

Why questions can be very useful for students. Being able to answer a “why” question can help them answer questions that show their knowledge and understanding of information, help them make sense of the world around them, and explain reasons for bad behavior and possibly keep them out of trouble. Here, in this page of 'You Must Know' we are providing answers to some “why” questions. 

Q: Why does a heavy meal bring about drowsiness?

    

      After a heavy meal the stomach and the intestines have a lot of work to do. Blood, with its precious cargo of oxygen and nutrition  rushes to the spot to help out.

  

      However, due to this diversion of blood, the brain receives less oxygen than it normally does. This makes it sluggish. And the result? You feel drowsy.

****

Q: Why does the shoe shine with shoe polish?

           

The surface of the shoe has tiny hollows and valleys. Light falling on an irregular surface gets scattered in all directions. Hence it does not shine. When we polish our shoes, the polish that we apply fills up the hollows. This makes the surface smooth causing the light falling on it to be reflected more evenly.

          As a result, the surface shines.

****

Q: Why do we get a fever when we’re ill?

A fever is one of the body’s ways of fighting infection.

          When illness strikes, chemicals called pyrogens are released which stimulate the brain to raise body temperature above its normal 98.6 degrees F. The extra heat is thought to speed up the immune mechanisms that fight harmful bacteria and viruses. However, if body temperature rises above 104 degrees F, headaches, fits and even damage can occur.

       Hence doctors advise us to keep fevers within the 100 to 102 degrees F range by using ice packs or taking drugs which inhibit pyrogens’ actions, such as aspirin and ibuprofen.

****

Q: Where do houseflies sleep?

“They don’t sleep as such,” explains Dr John Maunder, director of the Medical Entomology Centre in Cambridge, “but they do stop moving and rest in dim light.

          “Outdoors, when it’s dark, they tend to sit on the underside of a branch to protect them from the rain. In an unlit room they might sit under a table or chair.

         “You never see them there because they’re small and the room’s dark. And if you turn on the light, they will be immediately started to fly round again.

         “Even if you did see them, “Dr Maunder continues, you wouldn’t know that they were resting because they don’t have eyelids!”

****

Q: Why does water coming from a hot tap get warmer as you let it run?

When you turn off a hot tap, there’s always a little water left in the branch of pipe that lead to it. This water cools down and is then forced out first by new hot water when the tap is turned on again.

****

Q: What makes waves?

Far out on the ocean, the wind makes most waves. As the wind blows, it makes the top of the water bob up and down in ridges called waves. When a wave reaches shallow water, the bottom of the wave slows down. The top of the wave starts to curl over, and gravity brings it splashing down on the shore.

****

Q: Where does chocolate come from?

Chocolate comes from beans that grow on cacao trees. Cacao trees grow in countries where it is warm all the time. To make chocolate, the beans are roasted, removed from their shells, and ground up into tiny pieces. Oil from the beans is mixed with the pieces, and this mixture is used to make chocolate.

****

Q: Why does it snow?

There are tiny bits of ice inside clouds called ice crystals. Sometimes when it is very cold, the tiny droplets of water inside a cloud stick to the crystals and freeze. The ice crystals get bigger and heavier and heavier. When they are heavy enough, they fall to the ground as snowflakes

****

Q: What are goose bumps?

When people are cold or frightened, they get goose bumps. There is a little muscle attached to every single hair on our bodies. When we feel cold or afraid, each tiny hair muscle contracts, or shrinks, and pulls the hair straight up.

      As the hair rises up, it pulls on the skin and forms a little bump. We call this a goose bumps because it looks like the skin of a goose without its feathers