Q. & A.s SCIENCE & TECH. – 9

Q. &  A.s  ‑‑‑  SCIENCE  & TECH. – 9

246Q. What is the planet with the lowest escape velocity is?

The planet with the lowest mass. In our Solar System, that will be Mercury with an Ve of of 4.25 km/s

247Q. Why do the biggest planets have a bigger escape velocity?

The bigger planets have bigger atmospheres. Their mass is high.  

248Q. Which inner planet has the highest escape velocity?

Earth

249Q. Who were barefoot doctors?

After independence in 1949, in China, to meet the medical aid required to rural villages was provided through this system. For curing rural ailments, people who were volunteers were trained and sent to villages. MBBS doctors were not necessary to cure the simple diseases. These trained doctors were called barefoot doctors.

250Q. What is cryogenics?
Cryogenics is the study of the production of very low temperatures (below –150 °C, –238 °F or 123 K) and the behavior of materials at those temperatures.

251Q.What are cryogenic temperatures?
below -40 Degree .

252Q. What frozen treat was invented in 1988 using cryogenic technology?
Dippin’ Dots® are tiny, cryogenically frozen beads of ice cream, yogurt, sherbet and flavored ice.

253Q. What is cryogenic deflashing?
Cryogenic deflashing is a form of deflashing used to remove any excess plastic from parts that are molded. As molds wear and age they develop places where flash can occur.

254Q. How many countries having developing cryogenic technology?
Apart from India, there are five other nations which have developed & used this technology in their respective launch vehicles. Those countries are: CHINA EUROPEAN SPACE AGENCY JAPAN USA RUSSIA...

255Q. Why doesn’t Earth fall?

Earth is rotating around sun under its gravitational attraction. The gravitational attraction of the sun works like a stone that rotates around our hand when tied to a rope and rotated. To sun to its other end with gravitational attraction is tied with the earth. It goes on rotating. So there is no question of falling down.

256Q. How do igloos protect Eskimos from the severe cold?

1. When outside temperature is -40 degrees, inside temperature is 0 degrees.

2. Igloo is construction of ice and snow. These items work as insulators to trap body heat inside the igloo.

3. The walls block the wind which is often so bitter that it can make freezing temperature feel many degrees colder.

4. Several times melting and freezing makes igloo a solid piece.

257Q. Why is the water in an open pond cool even on a burning hot day?

The surface area of the pond is very large. More and more water is evaporated per second. As evaporation is more cooling is more. That is why water of a pond is cool.

258Q. How does the thermos keep the liquid hot for a long time?

Generally heat is lost into atmosphere through conduction, convection, and radiation. There is vacuum between layers of a thermos. The heat loss through three methods is the lowest. That is why tea remains hot.

259Q. Why is it cool in the morning and in the evening than in the midday?

In the morning and in the evening the sun’s rays fall slantingly. They have to travel long distance. In the midday, when rays fall perpendicularly, the distance travelled by the rays is the shortest. The gets hot soon. That is why midday it is hot.

260Q. why does swimming pool looks less deep than it really is?

When light travels from denser medium to rarer medium it bends and travels. This bending is the cause of a false image of the bottom. That image reaches us. So we feel that the swimming pool seems less deep.

261Q. Why do we need lightening arrester?

Lightening arrester is placed on the tallest building of that area. The lightening lands on the tallest building that is nearest to it. The whole building is damaged. To avoid this a metal piece of rod is placed on top of the building, from there a metal ribbon is connected to the ground. If lightening lands on the rod, it is taken to the ground without demolishing the building. It was invented by Benjamin Franklin.

262Q. What is nuclear fission?

The breaking of a large nucleus into small units is called nuclear fission. It happens in atom bomb.

263Q. What is nuclear fusion?

The combination of two small units of nuclei into a large one is called fusion? It happens in Hydrogen bomb.

264Q. All the protons are in a nucleus are positively charged. Like poles repel each other. Then why doesn’t nucleus explode?

Protons and neutrons are there in the nucleus. They won’t be in their state permanently. Neutron is a combination of a proton and an electron. Neutron becoming proton and proton becoming neutron is continuous process. That is why nucleus doesnot explode.

265Q. Are there electrons in the nucleus?

When neutrons disintegrate into protons and electrons they are emitted in the form of beta rays. Beta rays are electrons.

266Q. What is plasma state?

The ionized state of matter is called plasma.

267Q. What is hibernation?

When the existing atmospheric conditions are not suitable for living, animals go for sleeping for months together. It called hibernation. Eg., polar bear.

268Q. why kerosene is sprayed on water pools to eradicate malaria?

Malaria causing bacteria grow in stagnant water pools. The density of kerosene is very less. It floats on water spreading widely. When the larvae of malaria come on to the surface to take oxygen, this kerosene layer doesnot allow it. So larvae die.

269Q.  Why insulin cannot be taken orally?

If taken orally it goes to stomach and gets digested.

270Q.   why a pig’s blood is alternate to human blood?

Pig’s blood contains alfa galactose. It is more in that blood. It gives high immune system to our body.