Skip to main content

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...
Post a Comment

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 :

  1. Magnifiers
  2. Bifocal or varifocal spectacles
  3. Reading glasses

Labels:

Comments

Post a Comment

Popular posts from this blog

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...
1 comment
Read more

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.      
1 comment
Read more

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
Post a Comment
Read more