Keshav Jain

Keshav Jain

Why does it seem difficult to cycle up a steep hill than to push the bike up at the same speed?

A bicycle is unusual among machines because it has a mechanical advantage (MA) of less than one – typically between 1/3 (in low gear) and 1/8 (in top gear). This helps to convert effort to speed but also means that forces acting on the machine are multiplied by the reciprocal of the MA.

 When riding on the level, the forces of wind and road resistance are small so not much effort is needed, but when going uphill the force of gravity, is also multiplied up, making the journey more difficult.

 On steep hills it may therefore become easier to walk or run than to cycle. When you push the bike up a hill you tend to be doing about 4 or 5 kilometers per hour whereas while riding, even slowly it is at least 8 or 9 km/hr. Also while cycling up a hill our legs move at about half the rotational speed involved in walking, which means we will have to put in twice the amount of work.

Mountain bikers overcome this problem by having extremely low gears on their machines.

Cycling in a bike with low gears at 4 km/hr is surprisingly easy, so it need not be more difficult.

      

Who sent the first radio broadcast?

We know that Marconi was the first person to build a machine that could produce radio waves by making a powerful electric spark. His radio set could send messages, but the first radio broadcast occurred on Christmas Eve in 1906, and was made by Reginald Fessenden, a Canadian engineer, from Massachusetts in US. Wireless operators on ships at sea were the first people to hear this broadcast. They were amazed to hear a human voice coming from their instruments as someone spoke. Then a women’s voice rose in song! Many of them called their officers to come and listen, and soon, the wireless rooms were crowded. Next, someone was heard reading a poem. Then there was a violin solo… and then a man made a speech   In this first broadcast, Fessenden himself played ‘Holy Night, Silent Night’ on the violin. He also read Christmas story from the Bible (Book of Luke) and played a phonograph recording of Handle’s ‘Largo’. It was truly a Christmas Eve to remember!

 

Are phone lines just for voices?

Phone lines are not used only for conversations. If you have a videophone, you can actually see who you are talking to, as the phone lines are used for faxes through which you can send pictures, photos, and letters. Computers also use phone lines for an Internet connection, with which you can browse and chat for hours!

 

When were postal services mechanized?

Handling of mail often exposes postal workers to dust, especially when the mail bags are opened. Sometimes, dangerous chemicals may be split, and there are also electrical hazards that workers have to face. So postal systems have always been interested in mechanizing post offices. Between World War 1 and II, many postal systems introduced conveyor belts to move mail between handling points. The letter sorting office at Mount Pleasant in London was one of the most highly mechanized in the world Gradually, machines were introduced to prepare mail, and sort small letters from the bigger ones. There were also machines to stamp the date on letters and to put them neatly into sacks In modern, mechanized sorting systems, workers sit at a keyboard while letters are mechanically passed in front of them. Approximately fifty to sixty letters each minute are processed by the operator. Based upon the code entered by the operator, the letters are segregated into different bins, and then removed, bundled and dispatched by the postal workers

What were the problems faced by the early postal systems?

As postal systems developed, and the volume of mail they handled increased, many problems cropped up. To begin with, the cost of transport was high, and it was also difficult to calculate the exact cost of letters sent to other countries.Delivery was often slow, and this resulted in people using other means to send their messages. Many illegal postal services sprang up, causing financial losses to official postal systems. Gradually, these problems were overcome. The introduction of the postage stamp by Henry Bishop did away with uncertainties regarding that should pay the cost, and regularized charges. Since the day and month were also printed on the steps, unnecessary delays could be checked Today, we have speed post which guarantees 24 hours delivery to most places. We have come a long way indeed from the days when it sometimes took weeks for an urgent letter to reach us!

What is penny post?

In 1680, a merchant named William Dockwra organized the London Penny Post, which delivered mail anywhere in London for just one penny. He also introduced the practice of postmarking letters to indicate when and where they had been posted.The penny post had seven post offices, and 400 collection boxes throughout London. Letters were delivered ten or twelve times a day in the centre of London, and four or five times in the suburbs. However, the penny post became so successful that the government took control of the operation in 1682, and absorbed it into the Post Office. From then on, charges gradually increased, and letters were no longer delivered for a penny.

How was mail delivered in early times?

Today, the postman delivers your letters to your doorstep, but it was not always like that. In the early part of the 19th century, envelopes were not used. Instead, a letter was folded and the address placed on the outside of the sheet. The customer had to take a letter to the post office to mail it, and the addressee had to pick up the letter at the post office. In big cities in the USA, mail would be delivered home if you paid the carrier. In 1863, free city delivery was instituted in 49 of the largest cities in the USA. By 1890, 454 post offices were delivering mail to residents of United States cities. It was not until the turn of the century, however, that free delivery came to farmers and other rural residents

Who were post riders?

You might have seen your parents give a letter to someone who is going abroad so that they can pass it on to your relative who lives there. Well, in earlier times, when there were no postal services, this was how letters and messages were sent. This method of using travelers to deliver messages to other places developed into a system known as post riders.So we can say post riders were a horse and rider postal delivery system that existed at various times and various places throughout history. Post riders collected and delivered mail over the course of their route, meeting with other riders at scheduled times and scheduled places. Letters and parcels would be exchanged and forwarded to the next place by the riders. In this way, messages could pass a considerable distance

What is airmail?

Airmail is mail that is transported by aircraft. It arrives more quickly than mail that comes by road or ship, which is called surface mail. Airmail also costs more to send. If you want to send an urgent letter overseas, you have to send it by airmail. If you send it by ship, it could take weeks. In the case of airmail, the letter would reach its destination in days.