Text written in Basque and translated automatically by Elia without any subsequent editing. SEE ORIGINAL

On Science Video contest

The three first videos and the award ceremony that won the On Ciencia video contest.

The Doppler effect

Imagine you're in the
car. Do you see this sign that the speed of more than 80 kilometers per hour is forbidden? If you go faster, you can spot the radars, and you can
be fined. How does the radar work? Thanks to the Doppler
effect. The Deppler effect is the change in frequency in a wave when the observer or source is
moving. Let's give an example. This is the wave, and this is its frequency. Now
let's look at the different frequencies.
Just one more example. If we have a standing object, such as a wall, and we launch a wave, you will receive the same frequency when bouncing because the object or wall does not move. If we have an object that moves instead of
a wall, for example the car, when the radar launches the wave, the bounce will change the frequency. That's the
Doppler effect. By changing the frequency, the radar can see the speed of the moving object
or car. But how do you calculate the speed of the moving object? Well, about the Doppler effect formula.
This is the frequency that the radar emits. Here's the frequency that the radar receives. This is the speed of light, and this is the speed of the car. Let's do

a simple experiment. The materials we need are: the car, the computer with the Audicity program, the speakers and a microphone. This is our radar, the speakers are the transmitter, and the microphone is the receiver. We put the car at a speed of

80 kilometers per hour, we will emit a frequency of one kilohertz, and the frequency that we will receive is 1.14 kilohertz. If we pass this data to our formula, we will see that the approximate speed detected by the radar is 80.07 kilometers per hour.

Conclusion: The speed of a car is determined by the change in the frequency of the wave emitted by the radar.

AROUND THE BIRDS: THE FEATHERS

In places like this there are birds all the time, and in addition to feces we can find feathers. Feathers are the main characteristic of birds; in fact, all birds have feathers, while the rest of animals do not.

The first beings to have feathers lived 150 million years ago. The fossil of Archeopteris is a clear example. It had a skeleton resembling reptiles, and unlike birds, it had molars and tails. However, the sternum did not have the keel shape of today’s birds. That's why I didn't have enough muscle to fly. But the feathers were the same as today.

There are pens of many shapes, sizes and colors, but in general, they all have the same structure. They have a long axis called a spigot, to which are attached the feather burrs that make up the surface of the feather. Viewed from the microscope, these barbs branch into barbs that are attached to each other as if it were a zipper. In view of such a curious structure, the question comes to me: what are the feathers for?

The feathers help to fly; it seems obvious. They are stiff, very light, have perfect aerodynamics, but... are they useful for anything else? In fact, yes.

As the temperature drops, the feathers shrink and trap the air. This air is kept warm as if it were a layer that prevents the loss of heat. It is a very effective mechanism that we have imitated to make coats and quilts.

The pens are also waterproof. Protecting the animal from the rain prevents it from cooling down. In the case of waterfowl, total impermeability is mandatory because they are in contact with water at all times. If his body got wet, it would cool down immediately, and the bird would die.

The case of cormorants is striking. They don’t have very waterproof feathers and when they get in the water they get completely soaked. They often absorb so much water that it’s hard for them to even start their flight. They provide an effective and spectacular solution to the problem: spread the wings and dry in the sun. Sometimes shaking also helps.

For owls and motherfuckers, making noise while flying might have become a problem, but they have feathers covered with a furry, soft layer. Thanks to some of the blades on the front, the friction between the wings is also low. So they fly silently, becoming poachers.

Therefore, feathers are a treasure to take care of. It is essential to clean and take the bathroom a little often.

Even with maximum care, because they are made up of creatine and dead cells, the feathers wear out over time. Old ones need to be replaced by new ones.

For birds of prey it is essential to have a great ability to fly, because otherwise they would not be able to hunt. That's why it takes them two years to change their feathers. Sometimes the same animal can have up to three generations of feathers!

This is not the case with ducks. These birds change their feathers together at a certain time of year. Unable to fly, they seek the support of the group. They change all the pens at once because they do it twice a year. In this way, they have a plumage for the winter, which hardly distinguishes the male from the female, while in the summer season the males have another plumage, the wedding plumage. With this suit, the male changes completely.

In one way or another, all birds change their feathers and leave them where they are at that moment. Perhaps now, after what has been said, we will no longer see them as waste, but as excellent engineering work.