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What is friction and its types?

‘Friction‘ is a force that resists motion of sliding or rolling of one object moving relative to another. It is a result of the electromagnetic attraction between the charged particles of two touching surfaces. Types of Friction Static Friction : It is defined as the frictional force that acts between the surfaces when they are at rest with respect to each other. The magnitude of the static force is equal in the opposite direction when a small amount of force is applied. When the force increases, at some point maximum static friction is reached. Rolling friction : It is the force that resists motion when an object rolls on a surface. Technically it’s not friction; its ‘rolling resistance’ since when a body rolls perfectly upon a surface, on paper, there is no sliding friction between that object and surface. Sliding friction : It is the frictional force between two surfaces that are rubbing against each other. It’s a very easy and common concept. It’s hard to find a perfectl...

What is Presbyopia?

Presbyopia is the gradual loss of your eyes' ability to focus on nearby objects. It's a natural, often annoying part of aging. Presbyopia usually becomes noticeable in your early to mid-40s and continues to worsen until around age 65. Symptoms of Presbyopia People commonly mistake the symptoms of presbyopia for longsightedness. However, the two conditions have different causes: longsightedness is a result of a misshapen cornea, whereas presbyopia is due to the loss of flexibility in the lens. The telltale symptom of presbyopia is blurred vision while reading, sewing, using a mobile phone, or doing anything that requires near vision. Treatment for Presbyopia There are many options for people with presbyopia, including contact lenses. Recent technologies allow people who are entering into presbyopia to continue wearing contact lenses, instead of having to switch to bifocals, or reading glasses. Common treatments for presbyopia include : Magnifiers Bifocal or varifocal spectacles ...

Important question : Five question answers of electricity

Q1- What is the difference between a conductor and an insulator? Answer : A conductor allows current to flow easily through it. Insulators don't allow current to flow through it. Electric charges are absent in insulator. Conductors are used in making electrical equipment. Q2-What is electric current? Answer : Electric Current is the rate of flow of electrons in a conductor. The SI Unit of electric current is the Ampere. Electrons are minute particles that exist within the molecular structure of a substance. Sometimes, these electrons are tightly held, and other times they are loosely held. Q3-What is potential difference? Give its unit with definition. Answer : The amount of work done in moving a unit charge from one point to another is defined as the potential difference between any two points. Potential difference can be written as v = w Q . Here, w is work done and Q is charge. Volt is the SI unit of potential difference (V). Q4-What are the disadvantages of heating effect of c...

Definition of Impulsive Force

Impulsive forces are huge forces acting on a body for a short period of time causing drastic momentum changes . The SI unit of impulse is Newton-seconds (Ns) or kg m/s . Example of Impulsive Force

Heat and types of transmission of Heat

Heat energy is called Heat. When an object is very hot, it generally possesses a lot of heat energy; similarly, when the object is cold, it has less heat energy. Transmission of Heat The heat can be transferred from one place to another in different ways- Conduction Conduction mostly happens in a solid-state. All liquids (except mercury) and gases are poor conductors of heat. When a solid heat up, its molecules gain kinetic energy and increase the energy with which they vibrate. Conduction occurs when heat energy travels through a body, passing from one particle to another particle as they vibrate against each other. A good conductor must have particles that are close enough together to collide with sufficient force for energy to be transferred from one place to another. Convection Convection is the way in which heat flows through liquids and gases. Take a vessel of cold liquid soup on your stove and put it on the stove. The soup in the bottom of the pan, closest to the hea...

Newton’s laws

Born in 1643 in Woolsthorpe, England, Sir Isaac Newton began developing his theories on light, calculus and celestial mechanics while on break from Cambridge University. Years of research culminated with the 1687 publication of “Principia,” a landmark work that established the universal laws of motion and gravity. Force : The push or pull on an object with mass causes it to change its velocity. Force is an external agent capable of changing a body's state of rest or motion. It has a magnitude and a direction. (or Push or Pull on an object is called Force.) Newton’s first law: the law of inertia Newton’s first law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force. The law of inertia was first formulated by Galileo Galilei for horizontal motion on Earth and was later generalized by René Descartes. Although the principle of iner...

Newton’s Second Law of Motion

Sir Issac newton Born in 1643 in Woolsthorpe, England, Sir Isaac Newton began developing his theories on light, calculus and celestial mechanics while on break from Cambridge University. Years of research culminated with the 1687 publication of “Principia,” a landmark work that established the universal laws of motion and gravity. What is Newton’s Second Law of Motion? Force is equal to the rate of change of momentum. For a constant mass, force equals mass times acceleration. Newton’s second law states that the acceleration of an object depends upon two variables. The net force acting on the object and the mass of the object. The acceleration of the body is directly proportional to the net force acting on the body and inversely proportional to the mass of the body. This means that as the force acting upon an object is increased, the acceleration of the object is increased. then we can also that the mass of an object is increased, the acceleration of the object is decre...

What is the Law of Conservation of Energy?

The law of conservation of energy states that energy can neither be created nor be destroyed. Although, it may be transformed from one form to another. If you take all forms of energy into account, the total energy of an isolated system always remains constant. All the forms of energy follow the law of conservation of energy.

What is momentum?

Momentum of a body is defined as the product of its mass and the velocity. it has both magnitude and direction. Momentum(P) = mv where, m = mass, v = velocity

What is Pressure?

The amount of force exerted (thrust) on a surface per unit area is defined as ‘Pressure’. It can also be defined as the ratio of the force to the area. Formula and Unit of Pressure Pressure (P) = Thrust/ Area The SI unit is ‘Pascals (Pa)’ 1 Pa = 1 Newton per square m or 1N/m^2 Note : Thrust is the force acting normally on a surface. Its SI unit is Newton (N). Types of Pressure Atmospheric Pressure Absolute Pressure Differential Pressure Gauge Pressure

Why is the Earth called Blue Planet?

“The Earth has almost 70% water on its surface due to which it looks blue in color”. or “ More than 71% of the earth is covered with water. Hence, its is known as the blue planet ”. Why Earth looks blue from space? The Earth has extremely hot red heat under its crust and the top outer surface is covered with water. The Earth’s surface has many oceans and seas starting from the Arctic Ocean to the Southern Ocean. These oceans & seas cover almost 70% of Earth’s surface and the remaining 30% is covered with land. It means that almost 70% of Earth’s surface appears blue from outer space & the leftover 30% looks greenish-brownish. This is the reason why Earth looks blue from outer space.

Define Acids, Bases and Salts.

Acids, Bases and Salts : A substance that tastes sour in water, turns blue litmus red, and neutralises bases is known as an acid. If a substance’s aqueous solution tastes bitter, turns red litmus blue, or neutralises acids, it’s called a base. Salt is a neutral material that has no effect on litmus in aqueous solution. Arrhenius theory

What is matter?

Anything which has mass and occupies space is called matter. Or Everything that occupies the space and mass is called the matter. Or A matter is anything that has mass and occupies space. Such as Pen, paper, clips, sand, air, ice, etc. are different forms of matter. For Example : All living things like plants, animals, human beings can be called matter because they have mass and occupy space. All non-living things like water, oxygen, hydrogen can also be called matter because they also have mass and occupy space. Note : Every matter is made up of tiny particles. These particles are so tiny that they can't be seen with naked eyes. States of Matter : There are three states of matter. Solid Liquid Gas Solid : Matters which have fixed volume and shape are called solids. For example - stone, wood, brick, ice etc. All metals are solid except mercury and gallium. Properties of solids It has fixed volume. It has fixed shape. It has high density. It are heavy. It do...

What is non-metal?

A non-metal is a material which do not have properties of metals like lustre. They are non malleable, non ductile, non sonorous and bad conductor of heat and electricity. Example- Carbon, Sulphur, Phosphorous. Non-metals are the elements which form negative ions by accepting or gaining electrons. Non-metals usually have 4, 5, 6 or 7 electrons in their outermost shell. Very few elements in the periodic table are non-metals. These are present on the right-hand side in the periodic table. Elements that come under non-metals are sulphur, carbon, all halogens, phosphorus, hydrogen, oxygen, selenium, nitrogen and noble gases. Properties of Non-metals : High ionization energies High electronegativities Poor thermal conductors Poor electrical conductors Brittle solids-not malleable or ductile Little or no metallic luster Gain electrons easily Dull, not metallic-shiny, although they may be colorful Lower melting points and boiling point than the metals Some special facts : Uses of non-...

What is the properties of metal?

On the basis of their chemical and physical properties of metals are defined as elements that possess properties such as, malleability, ductility, sonorous, l ustre, conductivity and mechanical strength. They show the following properties. Malleable : Metals can be hammered into thin sheets. Ductile : They can be drawn into wires. Lustre : They have a shiny appearance. Sonorous : When we strike them, they make a ringing sound. Conductivity : Metals are a good conductor of heat and electricity. Mechanical Strength : It is the capacity or ability to withstand various loads without deformation or breaking.

What is metal?

Metals are opaque, lustrous elements that are good conductors of heat and electricity. Most metals are malleable and ductile and are, in general, denser than the other elemental substances. or Metal is a substance which is lustrous, sonorous, ductile, and is a good conductor of heat and electricity. or Metals are materials holding or possessing the characteristics of being shiny, hard, fusible, malleable, ductile, etc. Few examples of metals (materials) are – Gold, Silver, Aluminium, Copper, Iron, etc. or Metals are materials that are hard, lustrous, malleable, ductile, sonorous and good conductors of heat and electricity. Examples of metals are iron, copper, aluminium, calcium, magnesium, etc