Рет қаралды 73,656
DENJIRO: Today, I’m going to show you the power of friction. Take it away!
GIRL: He’s coming down on a rope!
DENJIRO: This is a technique known as “rappelling.” You may have seen a rescue squad doing this to save someone. Friction plays a big part in how he’s able to come down slowly.
The key is this tool right here. This is called a “figure eight descender” due to its shape. You put a rope through and wrap it around. You then attach it to a carabiner on your waist. Then, as you can see, it’s able to hold you up like this. Because the figure eight is getting pulled down, the friction between it and the rope increases, and the person doesn’t fall down. When you want to descend, you let up on the rope that you are pulling down on.
This reduces the friction, and you are able to descend. Supporting a weight of roughly 60kg is not easy, but this method allows for supporting his body weight with just the friction of the rope that’s wrapped around the figure eight.
Let me show you another experiment involving friction. A plastic bottle containing two liters of water and a banana are connected by a rope. What will happen if I just set the rope over this pole? I’m going to let go. I’m sure you could guess this would happen. Now watch what happens if I wrap the rope around the pole a few times. I’m going to let go.
GIRL: The banana is holding up the weight of the water!
DENJIRO: There is friction where I wrapped the rope around the pole, and that’s why the banana that weighs only 150 g is able to hold up the bottle that weighs 2 kg.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!"