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Friction (Objective Questions) | Class 8, CBSE (NCERT) Science


Class VIII, NCERT (CBSE) Science
Chapter 12, FRICTION (Objective Questions)
Q.1: Fill in the blanks:
(i) Friction always works in _______ direction of motion of the surface.
(ii) Friction depends on the relative _________ between two surfaces.
(iii) _________ is also produced with friction.
(iv) Shape of the objects moving in the fluid is _________ to overcome friction exerted by the liquids.
(v) ______________ are used in machines to protect their surfaces from wear due to friction.  
(vi) Soapy floor is slippery due to _________ friction.
(vii) Ball bearings are used to convert static friction into __________ friction.
(viii) Sliding friction is _______ than the static friction.
(ix) Friction increases with the increase in __________.
(x) __________ type of friction is the most powerful among all types of frictions.
Q.2: What causes friction between two surfaces?
Q.3: In which direction does friction work?
Q.4: What is done to tyres of the vehicles to reduce the friction? 
Q.5: What does friction produce?
Q.6: Name any machine where ball bearing is used to reduce friction.
Click here to see the Answers and More
Further study on this chapter
FRICTION | Class VIII, CBSE (NCERT) Science - Textbook Exercise Solution [Read]
FRICTION | Class 8, CBSE (NCERT) Science - Extrascore Notes and Questions [Read]

Class 8, CBSE (NCERT) Science, FRICTION - Sample Questions


Chapter 12, FRICTION
Class 8, NCERT (CBSE) Science
Additional Questions (Answers)
Points to remember
=> Friction is the force equal and opposite to the relative motion between the two surfaces in contact.
Q.1: What are the factors of friction?
Q.2: Can we eliminate friction completely?
Q.3: What causes chalk to write on the black-board?
Q.4: How does the nature of surface effect friction?
Q.5: It is easy to move an object on a sliding surface (inclined surface) than on a plane surface. Why?
Q.6: Why is it difficult to move an object from its static position?
Q.7: Why friction is called a necessary evil ?
Q.8: Why do we need to decrease friction?
Q.9: Explain the different types of friction. 
Click here to see the Answers and More
Further study on this chapter 
FRICTION | Class VIII, CBSE (NCERT) Science - Textbook Exercise Solution [Read]
FRICTION | Class 8, CBSE (NCERT) Science - Objective Questions [Read] 

Friction | Class VIII, NCERT (CBSE) Science, Chapter 12


FRICTION
Class 8, NCERT (CBSE) Science
Textbook Exercise Answers
Q.1: Fill in the blanks:
(a) Friction opposes the ________ between the surfaces in contact with each other.
(b) Friction depends on the ________ of surfaces.
(c) Friction produces ________.
(d) Sprinkling of powder on the carom board _______ friction.
(e) Sliding friction is __________ than the static friction.  
Ans: (a) relative motion (b) nature (c) heat (d) reduces (e) less
Q.2: Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Choose the correct arrangement:
(a) rolling, static, sliding
(b) rolling, sliding, static
(c) static, sliding, rolling
(d) sliding, static, rolling
Ans: (c)
Q.3: Alida runs her toy car on a dry marble floor, wet marble floor, newspaper and towel spread on the floor. What will be the force of friction in increasing order, acting on the car on different surfaces?   
Ans: wet marble floor, dry marble floor, newspaper and towel.
Q.4: Supposing your writing desk is tilted little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.  
Ans: Frictional force is acting opposite to the movement of the book i.e. upwards.
Q.5: You spill a bucket of soapy water on a marble floor accidentally. Would it make it easier or more difficult for you to walk on the floor? Why?
Ans: It is difficult to walk on a soapy floor because layer of soap makes floor smooth. The coating of soapy water reduces the friction and the foot can not make a proper grip on the floor and it starts getting to slip on the floor.   
Q.6: Explain why sportsmen use shoes with spikes.
Ans: Sportsman use shoes with spike to increase the friction so that the shoes do not slip while they run or play.
Q.7: Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?
Ans: Seema will have to apply larger force since; she will experience more frictional force because heavy object will be pressed hard against the opposite surface and produces more friction. 
Q.8: Explain why sliding friction less than static friction.
Ans: Sliding friction is always less than static friction because two sliding objects find less time to get interlocked against each other’s irregularities of surfaces as a result of which they experience less friction.    
Q.9: Give examples to show that friction is both a friend and foe.
Ans:
Friction is a friend because -
·         It allows us to walk comfortably.
·         It allows us to grip and catch other objects.
·         Things do not move from their places because of the friction.
·         Speeds of moving objects can be controlled due to friction only.
Friction is a foe because -
·         It causes wear and tear in objects of our daily use including machines.
·         It makes movement of heavy objects very difficult.
·         We need to spend a lot of time and money for the maintenance of various machines in order to keep their friction low.  
Q.10: Explain why objects moving in fluids must have special shapes.
Ans: The fluids like various liquids or air that is; gaseous medium also exerts frictional force known as Drag. To minimize the effect of this Drag, streamlining of the motion of the object in the fluid is necessary which can be achieved by modification in the shape of the body. Objects moving in fluids must have a special shape called streamlined shapes or aerodynamic shapes. Streamlined Shape or Aerodynamic Shape is that shape which overcomes the friction of fluid. They have pointed fronts with little broader middle portion with tapering at the back.       
Further study on this chapter
FRICTION | Class 8, CBSE (NCERT) Science - Additional Notes and Questions [Read]
FRICTION | Class 8, CBSE (NCERT) Science - Objective Questions [Read]

Congruence of Triangles (Chapter 7.1) | Class VII, NCERT (CBSE) Mathematics


Class VII, NCERT (CBSE) Mathematics
CONGRUENCE OF TRIANGLES
Text Book Exercise 7.1 Solution
(Page 137)
Q.1: Complete the following statements:
(a) Two line segments are congruent if __________.
(b) Among two congruent angles, one has a measure of 70°; the measure of the other angle is __________.
(c) When we write ∠A = ∠ B, we actually mean __________.
Ans:
(a) They have the same length
(b) 70°
(c) m ∠A = m ∠B
Q.3: If ΔABC ≅ ΔFED under the correspondence ABC ↔ FED, write all the Corresponding congruent parts of the triangles.
Ans:
If these triangles are congruent, then the corresponding angles and sides will be equal to each other.
∠A ↔ ∠F
∠B ↔ ∠E
∠C ↔ ∠D
CBSE | NCERT Solution: Class VII Math




Q.4: If ΔDEF ≅ ΔBCA, write the part(s) of ΔBCA that correspond to
(i) ∠E (ii)
cbse-ncert-solution.blogspot(iii) ∠F (iv) Class VII Math Solution
 

Ans:
(i) ∠C (ii) 
Class VII Math Solution(iii) ∠A (iv)  

Class 9, Natural Vegetation and Wild Life | Chapter-5, NCERT (CBSE) Geography (Contemporary India - I) | Sample Questions


Chapter-5, Contemporary India - I
Natural VEGETATION and WILD LIFE
Important Sample Questions
Q.1: Write a note on Tropical Evergreen Forests.
Q.2: Write a note on Tropical Deciduous Forests or Monsoon Forests.
Q.3: Write a note on Montane Forests.
Q.4: Write a note on Tropical Thorn Forests and Scrubs.  
Q.5: Write a note on Mangrove Forests (The Tidal Forests).
Further study (Link), on this chapter
Class IX Social Science (Geography) | Natural Vegetation and Wild Life | Chapter - 5, Contemporary India-I | NCERT (CBSE) Textbook Exercise Solution [Read]

Class 9, CBSE (NCERT) Economics | Chapter 4, Food Security in India | Sample Questions


Class IX, CBSE (NCERT) Economics
Chapter 4, Food Security in India
Important Sample Questions-Answers
Q.1: Explain the term ‘Food Security’. or What is ‘Food Security’?
Q.2: How is food security affected during a calamity?
Q.3: Write a short note on the role of cooperatives in providing food and related items.  
Click here to see the Answers
Food Security in India - Class IX, Economics
NCERT (CBSE) Textbook Exercise Solution [Read]

Class IX NCERT (CBSE) | Economics (Social Science) | Food Security in India

Class IX, NCERT (CBSE) Economics
Chapter 4, Food Security in India
Textbook Exercise Questions-Answers
Q.1: How is food security ensured in India?
Ans: The food security is ensured in India by the Government by carefully designed food security system. This system is composed of two components:
(a) Maintaining a Buffer Stock of food grains,
(b) Through the distribution of these food grains among the poorer sections of the society with the help of a Public Distribution System (PDS).
In addition to the above, the Government has launched several Poverty Alleviation Programmes (PAP) that comprise a component of food security. Some of these programmes are - Mid-Day Meals, Antyodaya Anna Yojana (AAY), and Food-For-Work (FFW) etc.
Besides the above, there are various cooperatives and NGOs such as Amul, Mother Dairy etc. who are also working intensively towards this direction.
Q.2: Which are the people more prone to food insecurity?
Ans: A large number of people in India suffer from food insecurity.
(1) In the rural areas the following types of people are more prone to food insecurity:
(i) Landless people with little or no land.
(ii) Traditional artisans who provide traditional services.
(iii) Petty self-employed workers.
(iv) Destitute including beggars.
(2) In the urban areas the following types of people are more prone to food insecurity:
(i) Casual labourers.
(ii) Workers employed in the ill paid occupations.
(iii) Workers employed in seasonal activities.
Incidentally these people suffering from food insecurity come from the regions such as economically backward states with high poverty, tribal and remote areas, and regions more prone to natural disaster etc.
Q.3: Which states are more food insecure in India?
Ans: The economically backward states with high incidence of poverty, tribal and remote areas, and regions more prone to natural disasters etc. are more food insecure in India. These states include Orissa (Kalahandi and Kashipur), Rajasthan (Baran district), Jharkhand (Palamau district), and parts of Uttar Pradesh, Madhya Pradesh, Bihar, Chhattisgarh, West Bengal and Maharashtra etc.      
Q.4: Do you believe that Green Revolution has made India self-sufficient in food grains? How?
Ans: When India became independent there was acute shortage of food grains. The country had to import large quantities of food grains from other countries. To meet this situation in late 1960s, the government adopted certain strategies in agriculture to make this country self-sufficient in food grains. These strategies included:
1. Use of HYV seeds.
2. Use of chemical fertilizers and pesticides.
3. New scientific methods of farming.
4. Several schemes for irrigation were undertaken to bring more land under cultivation.
All these resulted into ‘Green Revolution’ especially in the production of wheat and rice. Since the advent of the Green Revolution, India has not only attained self-sufficiency in food grains but also could avoid famine even during the adverse climates.     
Q.5: A section of the people in India is still without food. Explain.
Ans: In the newspapers, we daily read about the hunger deaths due to the shortage or non-availability of the food. Such news clearly proves that a section of the people of India is still without food.
In rural areas, the landless people, the traditional artisans, petty self-employed workers, destitute and beggars are always prone to food insecurity.
In urban areas too, the casual labourers, workers employed in ill paid occupations, workers engaged in seasonal activities are still with very little or no food at certain part of the year.      
During a calamity, the position of not only the above classes become from bad to worse but many people who become a victim of any calamity also have to face starvation.
No doubt, the government has played a key-role in eradicating food insecurity through buffer stocks, PDS and PAPs but sometimes such help reaches quite late and sometimes due to inefficient and corrupt officials a number of people are deprived of the benefits. Also, there are some lacks of proper monitoring of the schemes as some critics point out that in spite of overflowing granaries and FCI godowns overflowing with grains, a part of the people are still without food and the grains are being eaten by rats and some become rotten due to weather conditions. These are some of the reasons which are why a section of people in India are still without food.
Q.6: What happens to the supply of food when there is a disaster or calamity?
Ans: When there is a disaster or calamity the production of food grains decrease. This in turn creates shortage of food in the affected areas. Due to the shortage of food, the prices go up. When the prices rise many people can not afford to buy food. Thus, the food security of many people is adversely affected because of disaster or calamity. If such calamity happens in a very wide spread area or continues for a long period of time, it may cause a situation of starvation. Massive starvation can result into a ‘famine’.
Q.7: Differentiate between seasonal hunger and chronic hunger.
Ans: Hunger is an important aspect indicating food insecurity. It has two dimensions - seasonal and chronic.
Seasonal Hunger: Seasonal hunger persists only during a particular part of the season. It is linked with the cycles of food growing and harvesting. In the rural areas the seasonal hunger is prevalent because of the seasonal nature of agricultural activities. The gap between the sowing season and the reaping season is marked by seasonal hunger. In the urban areas the seasonal hunger is linked with the rainy season when there is less work for casual construction labour. This type of hunger exists when a person is unable to get a work for the entire year.
Chronic Hunger: When diet is persistently inadequate in terms of quantity or quality, it is called chronic hunger. Usually poor people suffer from chronic hunger because of their low income and as a result of their inability to buy food even for their survival. This type of hunger is more or less of a permanent nature and persists throughout the year.           
Q.8: What has our government done to provide food security to the poor? Discuss any two schemes launched by the government to provide food security to the poor.
Ans: The food security is ensured in India by the Government by carefully designed food security system. This system is composed of two components:
(a) Maintaining a Buffer Stock of food grains,
(b) Through the distribution of these food grains among the poorer sections of the society with the help of a Public Distribution System (PDS).
In addition to the above, the Government has launched several Poverty Alleviation Programmes (PAP) that comprise a component of food security. Some of these programmes are - Mid-Day Meals, Antyodaya Anna Yojana (AAY), and Food-For-Work (FFW) etc.
Antyodaya Anna Yojana (AAY)
This scheme was launched in December 2000. Under this scheme one crore of the poorer among the BPL families, covered by the Public Distribution System (PDS) were identified. Twenty-five kilograms of food grains were made available to each of the eligible family at a highly subsidized rate. After about two years, the quantity was enhanced from 25 kg to 35 kg. In June 2003, and August 2004, additional 50 lakh families were added to this scheme twice. In this way about 2 crore families have been brought under the AAY.    
Food for Work (FFW)
This programme was launched in November 2004 in 150 most backward districts of the country. The main objective of this scheme is to intensify the generation of supplementary wage employment. This scheme is open to all rural poor who are willing to do unskilled labour. In return of the work, the workers are supplied foodgrains or money as they like.  
Q.9: Why is the buffer stock created by the government?
Ans: A buffer stock of food grains is created by the government so that it can be distributed in the food deficit areas and among the poorer strata of the society at a price much lower than the market price. A buffer stock also helps to resolve the problem of food shortage during adverse weather conditions, disaster or calamity. Thus maintaining buffer stock is a step taken by the government in order to ensure food security.
Q.10: Write notes on:
(a) Minimum support price
(b) Buffer stock
(c) Issue price
(d) Fair price shops  
Ans:
(a) Minimum Support Price (MSP) - This is the pre-announced price at which the government purchases foodgrains particularly, wheat and rice from the farmer in order to crate a buffer stock. This price is announced by the government every year before the sowing season to give incentive to the farmers to raise the production of the desired crop. The rising MSPs have raised the maintenance cost of procuring food grains by the government as well as induced farmers to divert land from production of coarse grains to the production of these crops.
(b) Buffer Stock - It is the stock of food grains particularly, wheat and rice which the government procures through the Food Corporation of India (FCI). The FCI purchases these cereals directly from the farmers of those states where they are in surplus. The price of these commodities is much before the actual sowing season of these crops. The food grains thus purchased by the FCI are kept in big granaries and are called Buffer Stock. Maintaining buffer stock is a step taken by the government in order to ensure food security in the country.   
(c) Issue Price - In order to help the poor strata of the society, the government provides them food grains from the buffer stock at a price much lower than the market price. This subsidized price is known as the Issue Price.
(d) Fair Price Shops - The foodgrains procured by the government through FCI is distributed to the poor section of the society through ration shops. The Ration Shops are called Fair Price Shops because food grains are supplied to the poor through these shops at much reasonable and a fair price than the market price which is often high. Any family with a ration card can purchase stipulated amount of food grains, sugar, kerosene etc. every month from the nearby fair price shop.        
Q.11: What are the problems of the functioning of the ration shops?
Ans: The food procured by FCI is supplied to the poor through the ration shops which have been set up in most of the localities, villages, towns and cities. This is a part of the Public Distribution System (PDS) which is the most important step taken by the government towards ensuring food security in the country. These ration shops supply foodgrains, kerosene, sugar etc. to the poor at a price much lower than the market price. Any family with a ration card can purchase stipulated amount of these items every month from the nearby ration shop.   
But recently, many problems have crept up in the functioning of the ration shops, such as -   
1. The quality of the rationed articles issued to the poor is much less than what it should be. As a result the poor have to depend on the market for their needs.
2. Some of the ration shop dealers resort to malpractices. They illegally divert the grains to the open market for better gains.
3. Some of the ration shop dealers sell only poor quality of grains.    
4. Some dealers do not open their shops regularly and the poor people can not draw their ration quota timely.
5. Still others weigh less and cheat the illiterate poor fellows.
6. Some ration shops are unable to sell their poor quality grains, which become a great headache for FCI then.
7. With the introduction of cards and three different prices for the same articles to the different people, the whole system of PDS has become much complicated.
8. The APL card holders get very little discount at the ration shop because of which they have lost their interest to buy these articles from the ration shops etc.  
Food Security in India - NCERT (CBSE) Class IX, Economics
Additional Important Questions with Answers [Read]

Class IX NCERT (CBSE) Economics | The Story of Village Palampur | Sample Questions


Chapter 1, The Story of Village Palampur
Additional Important Questions
Q.1: What are the factors of production (resources required for production)?

Q.2: What is the main production activity in Palampur?

Q.3: What is ‘multiple cropping’?

Q.4: Who are farm labourers?

Q.5: What are the differences between ‘multiple cropping’ and ‘modern farming methods’?

Q.6: What is Kishora’s fixed capital?

Q.7: Would you agree that the distribution of cultivated land is unequal in Palampur?

Q.8: What is ‘Fixed capital’?

Q.9: What is ‘Working capital’?

Click here to see the Answers

Further study -
The Story of Village Palampur - NCERT (CBSE) Class IX, Economics - Text Book Exercise Questions Solved [Read]

Class IX NCERT (CBSE) Economics | The Story of Village Palampur


CBSE (NCERT) Textbook for Economics

Textbook Exercise Questions (Answers)

Q.2: Modern farming methods require more inputs which are manufactured in industry. Do you agree?

Q.3: How did spread of electricity help farmers in Palampur?  

Q.4: Is it important to increase the area under irrigation? Why?

Q.6: Why are the wages of the farm labourers in Palampur less than minimum wages?

Q.8: What are the different ways of increasing production on the same piece of land? Use examples to explain.  

Q.9: Describe the work of a farmer with 1 hectare of land.

Q.10: How do the medium and large farmers obtain capital for farming? How is it different from the small farmers?

Q.11: On what terms did Savita get a loan from Tejpal Singh? Would Savita’s condition be different if she could get a loan from the Bank at a low interest rate?

Q.14: What can be done so that more non-farm production activities can be started in villages?

Click here to see the Answers

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