Some countries, including the US, Canada, and Australia, use the 12-hour clock format including AM and PM. What do these abbreviations mean? We will discuss the meaning of AM and PM in this article.

AM stands for Ante Meridiam whereas PM stands for Post Meridiam. This is because the 24 hours of the day are divided into two periods- AM which means before midday and PM means after midday and each period comprises of 12 hours in number.

Hence, the term AM & PM is associated with the time-period: AM, is an abbreviation of the Latin phrase ante mer─źdiem meaning “before midday”; PM is an abbreviation of post mer─źdiem, meaning—“after midday.”

This rule gets a bit confusing when you take a look at 12PM and 12AM respectively. For example, 12AM - or ante meridiem - does not make logical sense when you look at the rule because it does not actually come after midnight. 

Therefore, it is always better to refer to 12PM as noon and 12AM as midnight respectively even if analog and digital clocks do label them as the former.

A 24-hour clock, sometimes referred to as military time, states the time according to the number of hours that have passed since midnight. Starting at midnight, hours are numbered from 0 to 24, removing the need for designations like am and pm. For example, at 23:00, 23 hours have passed since the beginning of the current day.


You must have noticed that every school bus has its school name written on it and is painted with yellow colour. Colors not only add to the aesthetic appeal of things, but they also make our lives much easier in many ways.In this article we will discuss the reason behind the yellow colour for School Bus.

Yellow (and the yellow family of colors) gets your attention faster than any other color. People notice yellow objects first.Even when you are looking straight ahead, you can see a yellow object that is not in front of you "in the corners of your eyes" much sooner than any other color even red. Scientists describe this as follows: "Lateral peripheral vision for detecting yellows is 1.24 times greater than for red."This means that as compared to the rest of the colours, yellow has 1.24 times more attraction and also more visibility. The yellow colour of the school bus is also known as the National School Bus chrome yellow.

If there’s fog or any kind of bad weather, drivers will still be able to see yellow cars and any moving vehicle fairly well.Not only are school buses yellow, but also many earth-moving, road-building and other outdoor machines are yellow because you could get hurt if you accidentally run into one of them. Many accidents occur in farms and outdoors because the victim saw the moving object too late. If it’s yellow, you have a strong warning!

This is why the school bus is painted with yellow so that the possibility of accidents on the highway will be less and children can reach their home safely.
Did you know that in the early 1930s, in the US, it was confirmed that there is more attraction in yellow colour than any other colours. That is why some signalling boards are painted with yellow colour.


CAPTCHA is abbreviated as “Completely Automated Public Turing test to tell Computers and Humans Apart”. CAPTCHA is basically a program that can tell whether its user is a human or a computer. They are colorful images with distorted text at the bottom of Web registration forms in many web application development websites. It was coined in 2000 by professors and scientists from Carnegie Mellon University and IBM.

Which purposes does CAPTCHA serve?

CAPTCHA prevents spam in website comment sections and on blogs. Many spammers bombard comment sections with links to increase search engine rankings. The test makes sure only humans comment and users don’t have to sign in beforehand to leave a comment.

It offers protection from scrapers who want to copy the email addresses of users. Spammers would crawl the Internet for email addresses that are posted in clear text. By utilising CAPTCHA you can protect against these scrapers. People need to solve a CAPTCHA before an email address is shown.

Importance of CAPTCHA:

1. Using CAPTCHA you can protect your website or blogs from comment spams, as bloggers receive more than 100 spam comments each day. You can seek help of web development companies to implement this.

2. It is essential that mainly free services should be protected with a CAPTCHA in order to prevent abuse by automated programs.

3. CAPTCHA also avoids dictionary attacks. These are the type of attacks under which an automatically generated scripts or computer program tries random passwords on login forms in case on unsuccessful login.

4. It helps search engines to prevent crawling the spam contents that may be harmful for keeping database safe or sensitive data of being exploited.


You might have heard about PSLV and GSLV rocket launch systems developed by the Indian Space Research Organization, or ISRO, to launch satellites into orbit.In this article we will understand the difference between PSLV and GSLV.

Let us understand this by an example:

Meet my 2 friends Polar and Geo.

I asked both of them to throw a 1.5 kg stone up in the air. Whose stone will go higher?
If everything is right, then normally Geo's stone will go higher than Polar's. Right?
Now if you ask Polar to throw a 0.5 kg stone, he may be able to achieve the same height as Geo's 1.5 kg stone. Whereas, Geo maybe able to throw three or four 1 kg stones to the same height as achieved by Polar's 1 kg stone.

This is the basic difference between GSLV (Geosynchronous Satellite Launch Vehicle) and PSLV (Polar Satellite Launch Vehicle).

Both PSLV (Polar Satellite Launch Vehicle) and GSLV (Geosynchronous Satellite Launch Vehicle) are the satellite-launch vehicles (rockets) developed by ISRO. The PSLV is the older of the two and the GSLV even inherits some of the technologies of the former in its design.

The main reason behind the advent of the GSLV is the capability to lift greater loads into space. While the PSLV can only lift slightly over a ton of payload to GTO (Geostationary Transfer Orbit), the GSLV is capable of lifting more than double that with a rated capacity of 2 to 2.5 tons. One of the main reasons why the GSLV has such an increased load is its utilization of a cryogenic rocket engine for its last stage. The cryogenic rocket engine provides more thrust than conventional liquid rocket engines but the fuel and oxidizer needs to be super cooled in order to keep them in a liquid state.

PSLV is a four-staged launch vehicle with first and third stage using solid rocket motors and second and fourth stages using liquid rocket engines. It also uses strap-on motors to augment the thrust provided by the first stage, and depending on the number of these strap-on boosters, the PSLV is classified into its various versions like core-alone version (PSLV-CA), PSLV-G or PSLV-XL variants.

The GSLV is designed mainly to deliver the communication-satellites to the highly elliptical (typically 250 x 36000 Km) Geosynchronous Transfer Orbit (GTO). The satellite in GTO is further raised to its final destination, viz., Geo-synchronous Earth orbit (GEO) of about 36000 Km altitude (and zero deg inclination on equatorial plane) by firing its in-built on-board engines.
When you look at their track records, it is easy to see that the PSLV is more reliable. With 18 launches, 16 of those were successes while only the first one was a total failure; the remaining one is called a partial failure as the satellite did not reach the intended altitude. The 7 launches of the GSLV have had worse results with 4 ending in failure and only two successes; it also has one partial failure launch.
In short:
1.The PSLV is older than the GSLV
2.The GSLV has a much greater load capacity than the PSLV
3.The GSLV use cryogenic fuel while the PSLV doesn’t
4.The GSLV has three stages while the PSLV has four stages
5.The GSLV has 4 liquid boosters while the PSLV has 6 solid boosters
6.The PSLV is more reliable than the GSLV


Tractors are extremely important agricultural vehicles. These machines are ubiquitous across the globe and range from rather small lawn tractors to giant monster worth hundreds of thousands of dollars. However, most of them have something in common – their exhaust pipes are pointing straight up in front of the driver’s cab. Meanwhile exhaust pipes of cars are located at the back, typically at bottom of the vehicle. Why is that? We will discuss the reason behind the vertical exhaust in this article.


Following are the reason why tractors have vertical exhaust :

1) Tractor is a off-road vehicle, usually used in every terrain including water dominated areas, where, there are chances of water to get in exhaust pipe and causing harm to the engine and exhaust system itself.

2) Mounting the exhaust pipe in the front has an added cost advantage – that’s where the engine is and less pipework is required this way. Less pipework – less maintenance as well.

3) Many chemicals are spread on crops or plants by driving tractor on the space between plants. If exhaust system is horizontal and below the driver them harmful and hot emissions can harm the crop.

4.)A normal tractor is constituted of two major parts – it can be split in two, which is occasionally done to repair transmission. Having an exhaust running from front to back would make such repairs hardly possible or very difficult.

Special note - Sometimes the end of exhaust pipe is curved, or has a hinged cover flap which the gas flow blows out of the way, to try to prevent foreign objects (including droppings from a bird perching, rain drops, ice on the exhaust pipe when the vehicle is not being used) getting inside the exhaust pipe.


You might have wondered why does almost every motorcycle have its exhaust placed on the right, and not the left?It is not a design constraint as such and you can have the silencer on the left as well. But there could be many reasons otherwise.We will discuss these reasons in this article.

Manufacturers have just stuck to the design that was implemented on the very first internal combustion-powered, single-cylinder motorcycles.The first motorbike without pedal was having exhaust on the right side. Since then manufacturers decided to mount the exhaust on the right side of the motorcycle.

Apart from this other reasons that are important to consider are as follows:

1. The exhaust fumes would be a little farther from the pedestrain walking sidewalks on the left.

2. Lot of women and old people sit sideways and it is much more safer to disembark them to the left. Silencer to the right helps with that.

3. Usually, there's a chain sprocket on the left side and having the silencer on the right balances the mass to some extent.

4. The way we learn to ride a bike, usually the left foot comes off the foot rest first when we are braking to a stop. Having the silencer to the right minimizes the risk of the foot coming in the proximity to the hot exhaust pipes.

But,it need not to be necessarily on right . Sports bikes have both sides , some have under the seat. But in general the exhaust is placed on the right side for above reasons.


Sometimes when you buy a strip of medicine (tablets), you notice of empty slots. Irrespective of the exact shape of the tablet, it can be round, rectangle, oval; every strip is packaged in this typical design-geometry.We will understand the reason behind the empty slots in this article.

Reason 1:

To keep up the standard size of the packing boxes, the company adds these extra spaces to avoid the extra cost.

Reason 2:

Since these tablets are small in size, but the minimum information required to be given on them is quite a lot, so the overall size of packaging is generally large so as to accommodate all relevant information.

Reason 3:

These extra empty spaces help to avoid breakage and spilling of medicines during transportation. This is one of the most important reasons why these empty spaces are there.

Reason 4:

This is a tricky one where our mind would get fooled by the packing. Extra spaciousness gives a feel that the tablet is worth the cost. But the actual fact is that it does not cost even an extra penny for the special packing!

Reason 5:

Empty space left is to increase the inertness of the tablet by pumping vacuum or inert gases inside the empty space. If air is present inside the empty space, then the tablets might get oxidized resulting in poor performance of the medicine.

Hope,this article might have helped you to understand the logic behiend those empty space.