Levers and Television
A boulder crashes through the ceiling, and Josie and Lester are not strong enough to shift it. Luckily Beakman is a lever lover. Then Philo Farnsworth, the man who invented television at the age of fourteen, drops in to explain how a picture gets from a camera to your screen, with Josie as the TV set.
How Can a Lever Make You Stronger?
A lever does not make you stronger. It makes the work easier with the strength you already have. Josie and Lester could not lift Beakman's boulder with their arms, but standing on the end of a seesaw they lifted it with a bounce. Every lever has three parts: the fulcrum it pivots on, the load you want to move, and the effort you put in. Move the parts around and you get three classes of lever.
We do not send a picture to your TV. We send instructions, and your TV makes its own picture. That was Philo Farnsworth's great idea. A camera turns a picture into a list of light and dark spots, line by line, a radio signal carries the list, and the set redraws the picture from it, thirty times a second. Josie did it with a walkie-talkie and five lines of black and white.
Have a Guess
Have a guess for each one before you tap. Trust your gut.
The boulder lifts. A seesaw is a first class lever, with the fulcrum between the effort and the load. Pushing down on one end swings the other end up. Josie and Lester are not one bit stronger than before, but the lever let them use their strength better.
It balances. The forks hang below the point where the toothpick rests, so the balance point of the whole thing, its centre of gravity, is below the support. Anything whose centre of gravity hangs below its support will sit there happily. Impossible, said Lester. Not impossible, said science.
About thirty times a second. The pictures on a TV do not move. You see a series of still pictures changing so fast that your eyes are fooled into seeing motion, just like a flipbook drawn on the corner of a notepad. That is how cartoons are made too.
Fast, Fun, Furious Facts
Eight fast facts from the show and the science. True or false? Tap fast, think faster.
Score:
Best streak:
Let's Find Out
Tap each card to find out more. Four cards for levers, four for television.
Key Ideas
The Three Parts of a Lever
Tap to learn moreEvery lever has a fulcrum, the point it pivots on; a load, the thing you want to move; and an effort, the push or pull you give it. The seesaw's fulcrum is its middle, the boulder is the load, and Josie and Lester bouncing on the other end are the effort.
Three Classes of Lever
Tap to learn moreIt is all about where the three parts are. First class: the fulcrum is between the effort and the load, like a seesaw, pliers, scissors or a car jack. Second class: the fulcrum is at one end and the load is in the middle, like a wheelbarrow or a bottle opener. Third class: the effort is in the middle, like a hammer, a tennis racket or your own arm.
Easier Work, Same Strength
Tap to learn moreThe further the effort is from the fulcrum, and the closer the load is, the easier the lift. That is why a long crowbar beats a short one and why you push a wheelbarrow by the ends of the handles. Third class levers trade the other way: a little movement at your elbow becomes a big fast swing of your hand.
Levers in Your Body
Tap to learn moreYour body is full of levers. Your elbow is a fulcrum: the biceps muscle pulls on your forearm, the effort, to lift a cup in your hand, the load. Because the muscle pulls so close to the fulcrum it has to pull much harder than the cup weighs, but your hand moves fast and far.
Instructions, Not Pictures
Tap to learn moreA TV camera takes a picture and turns it into instructions: a list of light and dark spots, line by line. Radio waves carry the instructions to every TV set, and each set draws the picture again from the list. Josie did it with five lines of black and white; a real set uses hundreds.
The Flicker Trick
Tap to learn moreThe pictures on a TV never move. The set draws a new still picture about thirty times a second, and your eyes blur them into motion. A flipbook does the same: draw a stick figure on each page, move its legs a little each time, and flip the pages fast.
Radio Carries the Picture
Tap to learn moreYou cannot have television without radio. The instructions for the picture are carried from place to place the same way sounds are carried to your radio, on invisible waves. Philo Farnsworth even predicted live news, sport and adverts, though not, he said, a grown man in a rat suit.
Today's Screens
Tap to learn moreModern flat screens still use the same trick. They are made of millions of tiny dots called pixels, each glowing red, green or blue, all changing together many times a second. Mix those three colours of light in different amounts and you can make every colour you see on the screen.
A Visitor From History
This week's Visitor From History had never been on TV before, which is odd, because he invented it.
Philo T. Farnsworth, an American farm boy who had the idea for electronic television at the age of fourteen, reportedly while ploughing a field in neat rows. On 7 September 1927, aged just twenty-one, he produced the first all-electronic television picture: a simple straight line.
He made Josie into a television receiver. Standing where she could not see the picture, he read it out over a walkie-talkie as a list of black and white spots, line by line, and she coloured in the squares. The picture is never sent. Instructions are sent, and the set makes its own picture. Then he went off to plan next season's schedule.
Try It: Lift the Boulder
Slide the fulcrum, choose how hard to push, and see whether Beakman's boulder goes up.
The rule of the lever: your push times its distance from the fulcrum must beat the boulder's weight times its distance. Move the fulcrum towards the boulder and a small push does a big job.
Use What You Know
Time to use what you know. Match the four things to their descriptions, then take on the challenge.
Match Them Up
Tap an item to pick it, then tap the box it belongs to.
Real World Challenge
Find three levers in your kitchen or garden and, for each one, point to the fulcrum, the load and the effort and say which class it is. (A bottle opener, a pair of scissors and your own forearm are good places to start.) Then make a ten-page flipbook on the corner of a notepad and work out how many pictures a second you need to flip to make the movement look smooth.
What Has Changed Since This Episode
This episode first aired in November 1992. Levers have not changed since the Greeks, but television has changed completely, and two of Beakmania's facts have been measured again.
Now we know: The lines have become dots. Television went digital, and the United States switched off the old signals in 2009. A modern 4K screen draws 2,160 lines of 3,840 dots each, about eight million dots, and redraws them 60 or more times a second. Philo was right about the big idea, though: it is still instructions, not pictures, and your set still draws its own.
Now we know: Those tiny teeth turned out to be remarkable. In 2015 engineers at the University of Portsmouth tested the teeth of the limpet, a sea snail, and found they are made of the strongest natural material ever measured, tougher than spider silk. Engineers are now copying the structure for cars, boats and aircraft.
Now we know: A little low. Better measurements put the brain at about twenty watts, roughly a fifth of what a laptop uses and still far less than any computer that can do what a brain does. That is one reason engineers study brains when they want computers to use less power.
Show What You Know
Answer these and get an instant tick or a nudge. How many can you get?
Results
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Think About It
Next time you open a door, work out where the fulcrum is and why the handle is on the far side from the hinges. Then watch a cartoon and try to spot a moment when the movement looks jerky. What is really happening on the screen?
Episode Discussion
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