When the body is in rest or have tendency to move then it has static friction and when the body is in motion, the kinetic friction may oppose or may support the motion depending on the conditions. The direction of frictional forces is opposite of the Applied force on the object.

For an object at rest on a flat table, static friction is zero. The maximum static friction force is: (fs)max = μs N where μs is the coefficient of static friction. Static friction is subtle because the static friction force is variable and depends on the external forces acting on an object.

Farmers take this huge responsibility of cultivation of crops to provide food to the entire population.

Various tasks performed by farmers for crop production are termed as Agricultural practices. Following activities form a part of Agricultural practices:

• Preparation of soil
• Sowing
• Adding manure and fertilizers
• Irrigation
• Protecting from weeds
• Harvesting
• Storage

Preparation of soil: Preparation of the soil involves loosening and turning it. This has the following advantages:
(i) Loose soil has a lot of air trapped in it, which is used by the roots to breathe easily.
(ii) Loose soil helps the growth of earthworms and microbes in the soil. They provide nutrients to the soil and aid in further loosening of the soil.
(iii) Turning and loosening of soil brings nutrient-rich soil to the top. Plants can then absorb these nutrients more efficiently.
The process of loosening and turning the soil is called tilling or ploughing.
It is carried out by using a wooden or iron plough which is pulled either by animals or by tractor.

Following are the advantages of ploughing the soil ---
1. It helps in turning the soil which helps bringing the nutrients from the soil to the top.
2. It helps in loosening the soil which helps the roots to penetrate deep in the soil.
3. It also help in proper mixing of manure in the soil.
4. It helps in preparing a good clean area for planting seed.
5. Ploughing improves the water retaining capacity of the soil.

Drip irrigation: Modern methods are the irrigation methods which are efficient in supplying water to the crops. They help us to use water economically without wastage. They include drip irrigation. Drip irrigation is the modern method which allows supply of water drop by drop directly near the roots to mininmise the wastage of water.  

Ruminants have one stomach with four compartments or chambers for digestion of food

Copper sulfate is a term that can refer to either of the following chemical compounds – cuprous sulfate (Cu₂SO₄), or cupric sulfate (CuSO₄). However, the latter is the preferred compound described by the term ‘copper sulfate’. The systematic name for CuSO₄ is copper(II) sulfate, but it is also referred to as blue vitriol, Roman vitriol, the vitriol of copper, and bluestone.

The term SI unit is the abbreviation of the French word Système International. SI or the International System of Units is now the most widely used system of measurement. The SI units have been in existence since 1960. This has replaced the varying measurement units and has made it easier to express the units universally.

The planets all formed from this spinning disk-shaped cloud, and continued this rotating course around the Sun after they were formed. The gravity of the Sun keeps the planets in their orbits. They stay in their orbits because there is no other force in the Solar System which can stop them.

Sometimes fertilizers get washed away due to excessive irrigation and are not fully absorbed by the plants. This excess fertilizer then leads to water pollution.

Continuous use of fertilizers in an area can destroy soil fertility because the organic matter in the soil is not replenished and micro-organisms in the soil are harmed by the fertilizers used.

Advantages of Fertilizer over manure:

(i) Fertilizers are very rich in plant nutrient whereas manure contains small amounts of essential plant nutrients.

(ii) Fertilizers are soluble in water whereas manure is not soluble in water.

• Viruses are smaller than any known cell.
• Viruses can only be seen with electron microscope.
• Viruses can reproduce only inside the bodies of other organisms, which mean they need a host.
• A virus is like a non- living thing outside the body of other organisms. Therefore, it is a borderline between a living and a non- living thing.

• The first step of cultivation is preparation of soil. This is done by loosening and turning the soil. A plough is used for this purpose. If the soil becomes too hard then farmer may resort to watering the soil before ploughing.
• Traditionally, animal-drawn ploughs have been used by farmers. Now-a-days, tractor-drawn ploughs are used for this purpose. A tractor helps in saving time and labour.
• The soil may contain many big lumps even after ploughing. The lumps are broken with the help of a hoe. Sometimes the farmer may add manure before ploughing; in order to properly mix the manure with soil.

Kharif crops: The crops which are sown in the rainy season are called kharif crops. They are grown between the months of June to September and are completely depend on monsoons. Example: Paddy, maize, cotton, soyabean, groundnut etc.
Rabi crops: The crops grown in the winter season are called rabi crops. They are grown between the months of October to march and are not depend on monsoons. Example:  wheat, pea, gram, mustard etc.

Bacteria are known for their simple body design. They are single-celled microorganisms with the absence of the nucleus and other cell organelles, hence, they classified as prokaryotic organisms.

1. Makar Sankranti

2. Baisakhi

3. Ladakh Harvest Festival

4. Lohri

5. Basant Panchami

6. Bhogali Bihu

7. Gudi Padwa

Plough is used for tilling the soil, adding manure and fertilisers and for scraping the soil.
Plough is an agricultural implement made up of two main components namely, plogh share and plough shaft.The main part of the plough is a long log of wood that is called a plough shaft.Plough share is the sharp and heavy piece of metal used for digging the soil.

The crops grown in the winter season are called rabi crops. They are grown between the months of October to march and are not depend on monsoons. Example:  wheat, pea, gram, mustard etc.

The crops grown in the winter season are called rabi crops. They are grown between the months of October to march and are not depend on monsoons. Example:  wheat, pea, gram, mustard etc.

<i>A Few Examples of Rabi Crops’ -</i>

• Chickpea
• Barley
• Flax Seed
• Pea
• Wheat
• Potato

Vaccines work based on the artificial acquired immunity concept. Here immune system is induced artificially by the injection of inactivated or killed pathogens. When same pathogen infect next time immune system is ready for attack immediately.