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How to ? Science And Technology Question & Answer – Part 5

Science Question and Answers Riddle Part 5

In How to know, about science and technology series we will provide you information about science and technology, We are in making part of series and every part will contain 8-10 scientific questions and answer !

HOW DOES A LIFT WORK?

The car of the lift that carries people up and down hangs from one end of a cable. An electric motor turns a drive pulley that winds the cable up and down. At the other end of the cable is a big weight called a counter weight. This is as heavy as the car and balances it.

The car runs between guide rails up and down the shaft. Controls inside the lift car operate the motor to take the car to any floor, and other motors open and close the doors.

HOW DOES AN ESCALATOR WORK?

Escalators are the moving stairs that carry people up and down in places like big shops. They move as fast as four metres a second. The steps of the escalator are connected by an endless chain that goes round and round without stopping. At the end, the steps go underneath the escalator and back to the beginning.

Near the top and bottom, the steps level out so that people can walk on or off the escalator. The motor that drives the chain connecting the steps together also drives the handrail through a set of gears.

HOW DOES А FIRE EXTINGUISHER WORK?

To put out a fire, the extinguisher sprays out liquid or a vapour or foam. This cools the fire and also covers it to stop air from getting to the fire, One common type of fire extinguisher sprays water.

Inside a water-filled extinguisher is a bottle of sulphuric acid and a solution of sodium bicarbonate. To use this extinguisher, you turn it upside down or strike a knob.

HOW DO ROBOTS WORK?

Most robots consist of a mechanical arm with a gripper like a pair of tongs at one end. Inside the arm are hydraulic motors that can move the arm and gripper in any direction. The arm is connected to a box of controls that operate the motors to make the robot perform a particular action.

The robot is first taught the various movements that it must make. The controls contain a memory like a computer memory to make the robot carry out a different task.

HOW ARE DAMS BUILT?

A dam is a huge barrier built across a valley so that river water piles up behind it to form a lake. Many dams are constructed by heaping up earth and rock, while others are made of concrete or stone blocks.

An earth-fill dam is made with a solid core of clay surrounded by earth and gravel and covered with rocks.

Buttress dams are thin dams built with supports called buttresses to hold them up. Arch dams have high narrow walls that are curved.

HOW DOES A COLOUR PRINTING PRESS WORK?

Even though they look multi-coloured, the colour pictures in books and magazines are printed in only four colours. The press prints the picture separately in red, yellow, blue and black, These four coloured pictures overlap and we see the picture in full colour.

The printing press has four printing plates that are fixed to cylinders. Each plate has an image of the picture on it. The paper passes through four sets of cylinders, and the four images build up to give a full, colour picture.

HOW ARE BOOKS BOUND?

Binding a book means putting the pages together and fitting its cover, The pages come in sections like thin books. The sections are placed in order and sewn together with strong thread. The cover is then glued on to the back and sides of the book.

Separate end papers are often attached to the book when the page sections are sewn together. The back is then glued to keep the pages in place, and the pages are trimmed with knives to make them even. Then the book is placed in a frame and the back hammered to round it, and a lining is glued to the back to reinforce it.

HOW DOES A TYPE-WRITER WORK?

A typewriter has a set of keys marked A with letters, numbers and signs. When you press a key, it marks the paper held against the cylinder. A type bar connected to the key strikes an inked ribbon, and the ribbon marks the paper. A spring then pulls the cylinder, moving the paper along to the next position.

A system of levers and springs connects each key to its type bar. Each type bar has two letters (one capital letter and one small letter) or a number and a sign or two signs. The typist selects one of these by pressing a shift key that raises or lowers the type bars.

HOW DOES A TELEPRINTER WORK?

A teleprinter is a kind of typewriter that is used to send written messages by telephone. Instead of speaking on the telephone, a message is typed out on the teleprinter. The letters are changed into electric signals, which go along the telephone wires to a teleprinter at the other end. This types out the message.

The telephone system used for connecting teleprinters is known as Telex. Any teleprinter in the Telex network can be reached simply by dialling its number.

HOW DOES A CALCULATOR DISPLAY NUMBERS?

The numbers on a calculator’s display A are all made of straight lines in different patterns. All of them seen
together give 8. Wires connect each of these lines to the calculator’s electronic brain. Electric signals go to the display, and light up some of the lines to produce numbers.

Calculators have two different kinds of displays. LED displays have numbers that glow brightly, usually in red. The displays which do not glow but show up rather like numbers on paper are called LCD displays.

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