My Science School

To use a handheld mixer, you first plug it in and attach two balloon whisks. Place the mixer in your bowl of ingredients and select the speed setting you want. Turn it on by pushing a switch. The whisks start to rotate due to an electric motor inside the device. The whisks will mix, beat or whip the ingredients, depending on your speed setting. They will also incorporate air into your ingredients, giving them a "fluffier" texture. You often move the bowl while using your mixer, to make sure every ingredient is thoroughly mixed.

A stand mixer works similar to a handheld, with the difference that you attach a bowl (often a stainless steel bowl) to it and you do not have to hold the mixer. After affixing the bowl to the mixer, you add the preferred attachment (such as a dough hook for bread ingredients) and select the desired speed setting. You then flip the switch, and a large motor will rotate the attachment. Let it work as long as it needs. You may have to scrape the attachment during the mixing, such as when too much of the dough sticks to the hook.

 

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A pushchair is ideal for older babies at around 6 months. A good way to judge if a baby is ready for a pushchair is if they are able to sit up unaided. A pushchair generally offers the option for the baby to be forward-facing too and in this position, it's sometimes referred to as a ‘buggy’ which is another term that is used interchangeably.

A travel system consists of a pushchair frame, upon which other parts can easily be fitted. These parts include carrycot, seat unit and a rear-facing car seat and are purchased together as a package which often makes a travel system good value for money.

However, travel systems don’t always have to be bought together as a package, alternatively, you can buy the elements separately.

Most pushchair brands include compatible car seat adaptors in the travel system package enabling the infant car seat to easily be clipped onto the wheels so that a sleeping baby can be moved seamlessly from car to pushchair.

Many car seat manufacturers recommend that a baby should spend no longer than 2 hours (30 minutes for newborns) in a car seat within a 24 hour time period. The benefit of a travel system bundle is that it includes all the parts needed to grow with your baby- once the baby has outgrown the car seat and carrycot, the seat unit can be used.

 

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Escalators are one of the largest, most expensive machines people use on a regular basis, but they're also one of the simplest.

At its most basic level, an escalator is just a simple variation on the conveyer belt. A pair of rotating chain loops pulls a series of stairs in a cons­tant cycle, moving a lot of people a short distance at a good speed.

The core of an escalator is a pair of chains, looped around two pairs of gears. An electric motor turns the drive gears at the top, which rotate th­e chain loops. A typical escalator uses a 100 horsepower motor to rotate the gears. The motor and chain system are housed inside the truss, a metal structure extending between two floors.

Instead of moving a flat surface, as in a conveyer belt, the chain loops move a series of steps. The coolest thing about an escalator is the way these steps move. As the chains move, the steps always stay level. At the top and bottom of the escalator, the steps collapse on each other, creating a flat platform. This makes it easier to get on and off the escalator. In the diagram below, you can see how the escalator does all of this.

Each step in the escalator has two sets of wheels, which roll along two separate tracks. The upper set (the wheels near the top of the step) are connected to the rotating chains, and so are pulled by the drive gear at the top of the escalator. The other set of wheels simply glides along its track, following behind the first set.

 

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Cranes combine simple machines to lift extremely heavy objects. In balance-style cranes, the crane’s beam is balanced at a point, called the fulcrum. This allows it to lift heavy objects with a relatively small force. In this way, the crane’s beam acts as a simple lever. Cranes also make use of the pulley, another simple machine. Tower cranes often have more than one pulley. This helps it multiply its force to lift heavy objects.  

Cranes exist in an enormous variety of forms, each tailored to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for constructing high buildings. Mini-cranes are also used for constructing high buildings, in order to facilitate constructions by reaching tight spaces. Finally, we can find larger floating cranes, generally used to build oil rigs and salvage sunken ships.

Some lifting machines do not strictly fit the above definition of a crane, but are generally known as cranes, such as stacker cranes and loader cranes.

 

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Shopping carts (also known as shopping trolleys or shopping baskets in some parts of the world) are a great example of a simple machine at work. They consist of only two main parts: a metallic basket and a set of wheels. The basket has a handle attached to it (which helps in steering the cart), and it’s installed above a set of four small wheels that make pushing, pulling and steering the cart very convenient.

It’s quite clear that a shopping cart consists of very simple components, but it is of tremendous assistance to shoppers while they roam throughout the shopping mart looking for a particular flavor of cookie or a big bottle of anti-dandruff shampoo.

In some countries, including India, the United Kingdom and Australia, there is a rather queer problem with trolleys; they seem to have a mind of their own! Suppose you try to turn a trolley towards, say, the left. It would definitely turn, but not towards the left; it would either go towards the right or move straight ahead. The same thing happens when you push them in the forward direction; it goes left or right unless you apply a surprisingly large amount of force to move it in the desired direction.

 

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The earliest wheel and axle machines were used as potter’s wheels. A potter’s wheel is a flat, round stone. By applying effort to a pedal, the potter makes the stone spin on its axle. The potter works a piece of clay between her hands on the spinning stone, shaping the clay into a pot. Clay pots were very important in everyday life in ancient times. They were used to store food, water, and medicines.

A potter's wheel may occasionally be referred to as a "potter's lathe". However, that term is better used for another kind of machine that is used for a different shaping process, turning, similar to that used for shaping of metal and wooden articles.

The techniques of jiggering and jolleying can be seen as extensions of the potter's wheel: in jiggering, a shaped tool is slowly brought down onto the plastic clay body that has been placed on top of the rotating plaster mould. The jigger tool shapes one face, the mould the other. The term is specific to the shaping of flat ware, such as plates, whilst a similar technique, jolleying, refers to the production of hollow ware, such as cups.

 

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CD-ROM’s are important tools for computer users. CD-ROM’s are discs that store words, music, and images. Encyclopedias, games, and other programs that would require greater storage capacity can fit onto one CD-ROM. CD-ROM stands for computer disc read-only memory.

When you put a CD-ROM into your computer’s drive, files are copied from the disc to the computer’s hard drive. These files tell the computer how to access all the information on the CD-ROM.

A DVD (digital video disc) is the same size as a CD-ROM but can store much more information. Unlike a CD or CD-ROM, the DVD is able to record data (information) on both the top and the bottom of the plastic disc. And it can record two layers of data on each side. A DVD player can also play CD-ROM’s.

A DVD contains layers of digital data encoded in tiny pits. In a DVD player, a lens focuses a laser beam on the desired layer. As the disc rotates, the pits and the flat areas between them reflect patterns of light to a photo detector, which changes the patterns into electrical signals. A single layer of a DVD has more pits, placed closer together, than an ordinary CD has, and so can store more data.

 

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Computers save us a lot of work—and a lot of time. The processor of the computer follows step-by-step instructions-exactly and quickly. This series of steps is called a program. A program might be thousands of steps long, but the processor can run the program in less than a second.

The program is stored in the computer's memory. It is stored as a series of 1's and 0's. This is called a digital code. Sometimes the code is stored on a CD-ROM or inside the computer on the hard drive. But the computer finds it when it needs it.

When you have finished a report, you tell the computer to print it. The computer sends the digital code to the printer. The printer has a microprocessor that changes the code into letters—so you and your teacher can read it.

Laser printers are the fastest printers. A beam of laser light makes an electrically charged image on a rotating, cylinder. The charged areas attract powdered or liquid ink called toner, onto the cylinder. The cylinder transfers the toner with the image onto the paper. The paper then passes through fuser rollers. These rollers seal the toner to the page so it doesn't smear.

 

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As electricity moves through the circuits in the computer, millions of tiny switches are turned on and off. The computer reads a code of zeros and ones. Think of the code as switches in a line. The ones are switches that are turned on, the zeros are switches that are turned off.

The code is called digital. Because it uses only two numbers in different patterns, it is also called binary code. When you type an A on the keyboard, the computer stores the A in its memory as 01000001. Each time you click the mouse, or press a key, it is changed to binary code and stored in the computer's memory.

It’s not only numbers and text — binary is used for the most complex data. From images to video frames, at the most granular level of the data, it is binary code.

For example, an image is built up of hundreds of thousands of pixels, with each pixel containing an RGB value stored in binary code.

These binary codes fill RGB and according to the intensity generated from those codes, the intensity numbers are thrown at a video driver program. That program distributes those colors to the million crystals on your screen — and an image is seen by us!

 

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Telephones have them. Most watches have them. They help make our cars safe. They make our telephones work more quickly. And space travel would be impossible without them.

They are microprocessors. They make our lives easier in many ways. A microprocessor is a type of microchip that can hold the signals needed to run electronic devices. Some microchips only store information. But if the microchip is also able to "figure things out," then it's called a microprocessor. A microprocessor works faster than your brain. And it can fit on the tip of your finger!

The surface of this tiny part is cut with grooves. Each groove is packed with thousands of tiny electrical switches. The switches are connected by thin metal wires. All the wires link together-a group called a circuit.

Microprocessors are also called integrated circuits. Equipment such as calculators made with integrated circuits are small, light, and easy to use.

When you use such equipment, bursts of electric currents speed along the circuits. These bursts are like messages. They tell the equipment what to do.

The most important part of a computer is its microchip, or integrated circuit. A microchip can fit on a fingertip. When seen under a microscope, the tiny grooves and wires look like a maze.

The first integrated circuit was made for the U.S. space program in 1959. Equipment on the spacecraft had to be very small. All electrical signals for the equipment were put on a strip of material called silicon. Later, circuits were made into tiny squares called silicon chips.

 

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Look at a picture of yourself. Now look at it from a different angle. Do you see another side of yourself in the picture? No, but if you were looking at a hologram you could walk around the picture and see the left side of your body, your back, your right side, your front, and the top of your head.

A hologram is an image that looks three dimensional-that is, it seems to have depth, height, and width. Some credit cards have holograms on them. Holograms also appear in advertisements, artwork, and jewellery.

A hologram is made with laser beams. A laser beam is a kind of coloured light. One laser beam is bounced off a mirror then off the subject and onto a special film. Another laser beam is also bounced off a mirror and onto the film. Where the two beams cross on the film, they make a tiny pattern of bright and dark stripes, a hologram.

Guiding a laser beam onto the film will produce light rays that seem to come from the original subject. The resulting three dimensional image appears to hover in space. You can look over, under, and around the subject. When a hologram is viewed with regular light or sunlight, the image appears with rainbowlike bands of colour.

To make a hologram of an object, such as this teddy bear, a laser is aimed into a mirror then at the object. Another laser is reflected off a mirror and then onto the film. The film records the hologram.

 

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Is a DVD the same thing as a CD? Although DVD's looks like CDs, they are different. A DVD works like a CD, but it can hold more information. A CD usually records only sound, but a DVD records pictures as well as sound.

Each side of a DVD can contain two layers. Each of these layers can store data. CD's have only one layer of information.

Before CD's and DVD's were invented, people used cassette tapes and videotapes. Cassette tapes record and play sounds, and videotapes record and play sounds and images.

Cassette tapes, videotapes, CD's, and DVD's can be played again and again. That's one of the reasons people like them so much.

A DVD can be played in a DVD player. A DVD player is often connected to a television set. When a DVD is played, pictures appear on the TV screen and sound comes out of speakers.

 

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Cassette tapes sound good when they are new. But after a while, they start to sound scratchy. A compact disc, or CD, produces much better sound. It is played using a special light called a laser beam. Only the beam of light touches the CD, so it stays like new.

Sound is stored on a CD in a digital (numerical) code-a string of 0's and 1's. When a CD is made a microphone turns sound vibrations into electrical signals. Then a machine changes the signals into a digital code.

This code is fed into a powerful laser. As a blank disc turns, the laser cuts billions of tiny pits that represent the digital code into the surface of the disc.

Inside a CD player is another, less powerful, laser. When the CD is played, the laser reads the position of the pits. The laser reads from the centre to the edge of the disc as the CD turns. These pulses of light are turned into electrical signals. The signals make the speakers vibrate. Then you hear the sounds.

Inside a CD player, a laser beam shines on a mirror and through a lens onto the pits on the CD. When the beam hits a pit, the light is scattered. When it hits between pits, the light is reflected straight back. A sensor reads the patterns of reflected light and turns the patterns into electrical signals. These signals are used to produce sounds.

 

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You probably don't think of a toilet as a machine. But that's what it is. You press down the flush lever, and the toilet does the work.

Most toilets have two main parts-a tank and a bowl. The tank sits on the back of the toilet bowl. Both contain water. The bottom of the tank has an opening with a plug. The plug keeps the water in the tank from flowing into the bowl. Pushing down the lever to flush the toilet lifts up the plug.

Water then rushes out of the tank. It flows into the toilet bowl through small holes all around the rim of the bowl.

The fresh water pushes the dirty water into the drainpipe. The plug closes when the tank is empty. Fresh water then flows through an inlet tube into the tank. And the tank is ready for the next flush.

 

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With a hairdryer, we don't have to wait for our hair to dry.

Inside the hairdryer, electricity travels on a pathway of wire. The electricity travels easily on most of the wire in the pathway. This is called conducting electricity. The path is open. The electrons in the wire are free to move.

But some metals resist, or slow down, the electric current flowing through the hairdryer. When the electrons slow down, they bump into one another as they move through the wire.

Then the wire heats up. The harder they bump and push, the hotter the wire gets.

When you plug in a hairdryer and turn it on, electricity travels through it. It powers a tiny fan. Then the electricity travels to coiled wire made of resistant metals. These wires heat up. The fan blows heat from these wires out through a vent. This is the hot air that dries your hair.

Inside an electric hairdryer, there is a coil of wire that heats up. The fan blows the heat out to dry your hair.

 

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