Friction is a Force)

Hi, I am Jared. Welcome to Fun Science Demos. The big idea today is that friction is a force, and through science we have discovered that friction happens anytime two things rub against each other. Friction wants to slow things down. So I have a really simple setup. I have a cardboard ramp and a plain wooden block. Why is the block not sliding down the ramp? The force of gravity wants to pull that block down the ramp. What is keeping it still? The force of friction. The force of friction is actually stronger than the force of gravity. I am going to raise my ramp. What happened was the force of gravity became stronger than the force of friction. Friction held the block in place. Gravity was just too strong, and it overcame the friction. Through science, we have discovered that the force of friction is different with different surfaces. I have a wooden block that is plain and smooth, and the same wooden block, but I have attached a piece of sandpaper, and then another same wooden block, but I have wrapped it in aluminum foil. Now through science, we have discovered that the friction is different on these different surfaces. Let us check it out. I am going to slowly raise the ramp. Which block do you think will slide first? Which block do you think will slide last? Friction. Here we go. Now the trick to make this work is you have to go slowly and steadily. I see some movement. Wow! The aluminum foil slid first. Which do you think is going to be next? Keep raising the slide higher. The plain block went next. You can even see the friction in action here. It is hanging on. It does not want to move. The sandpaper goes down. Look at the height of that ramp. Friction in action. Science is so cool. Friction is all around us, not just on sliding boards. Take a look at this. I have two pieces of plastic. I am going to try and spin both of them. Why did it stop spinning? Well, the friction slowed the block down and stopped it from spinning. Check it out. Same block. Why did it spin so much longer? Well, so how did we cut down the friction? Well, little glass marbles. The little glass marbles reduce the friction. Believe it or not, it is a lot like your bicycle wheel, or your skateboard wheel, or even a car tire. They do not have little glass balls in them. They are actually little metal balls called bearings, and you cannot always see them because they are packaged up so they do not rust, nothing happens to them, but it is meant to reduce the friction so your tire spins more easily. Friction is a force. Thanks for watching. Do not forget to check out our links in our video description.