Do you know what would happen if you tried to slide across pavement in your sneakers? Most likely you’d fall and hurt yourself. What about sliding on a polished marble floor in your socks? You’d probably be able to travel several feet before stopping. These all seem like easy to understand concepts, but do you know why this happens?
The answer to the above questions is because of friction. Friction is the force that prevents movement of an object when it rubs against another object. The rougher the surface, the more friction, thus the more likely the object will not be able to slide. Less friction means there is less force preventing an object from braking.
If you’re interested in the concept of friction and what it means for everyday objects, then read the list below containing 10 fun and interesting facts about friction.
- Liquid causes a surface to become “smoother” and creates less friction. For instance, it’s much harder for a car or runner to stop on a wet road than it is on a dry one because the water here creates an obstacle between the car and the road. This causes the car’s tires or the runner’s rubber soles to have less contact with the road, meaning that they’ll have less “grip” to stop their forward motion.
- A car engine needs a regular application of oil on certain components, specifically car parts that are in constant contact with one another. This oil, known as a lubricant, keeps the parts wet and slippery, thus creating less friction. If you rub your hands together, you’ll find that your palms will become increasingly warmer the longer you rub them. The same concept can be applied for car engines and brakes: the longer they are in contact with each other, the hotter the parts will become. It’s important to add a healthy dose of oil regularly to prevent unwanted damage on your car engine and brakes.
- When an object rubs against another, it will tend to slow down or at least require more energy to continue (try rubbing your hands together for 5 minutes and see how tired you get). The energy used to move the objects is converted from kinetic energy to heat energy.
- In addition to lubricating an object or making an object wet, surface area also plays an important role in creating friction. Surface area refers to how much of an object’s area is in contact with another. Generally speaking, the more surface area touching an object, the more friction there will be, meaning the harder it is to continue moving. For instance, if you look at your ice skates, you’ll see the blade is extremely thin. This is made to eliminate friction so skaters require less energy to move and perform awesome spins and tricks.
- If you have ever seen a horse carriage, there are three important things to consider. First, how well the horse’s hooves can grip the ground. A horse needs a good grip on the ground’s surface to pull the carriage forward. Second, the wheels of the carriage. Wheels are perfect for moving objects forwards and backwards because their unique shapes means that there is less surface area touching the ground. Third is the weight on top of the carriage. If a 500 lbs man were sitting on top of a carriage, although the carriage is resting on wheels, it can be difficult for the horse to move forward.
- Children can cause destruction at home (either intentionally or unintentionally). An easy example is dropping a plate from the dinner table to the floor. The plate slides of a polished wooden table because the table is lubricated/moistened by the polish, and a ceramic or plastic plate will not cause much friction. Imagine if the bottom of plates were covered with rubber – a substance that can grip onto surfaces more easily (like car tires). Perhaps we would have less broken dishes and less spankings.
- If you have a carpet at home, try rubbing your feet whilst wearing socks onto the carpet’s surface. After doing this for about 30 seconds, your body should have enough static shock to either shock yourself when you reach for a metal doorknob, or shock your brother/sister/mom/dad if you poke them. This is because the friction causes between your socks and the floor sends opposing electrical charges to each other, building up a shock that can sting others when touched.
- Going back to the previous example, if you rub your elbow or knee against a carpet without any protection, most likely you’ll experience a burning and stinging sensation. This is known as carpet burn or rug burn, and friction plays a large role in creating that shiny blister. Carpets and rugs are extremely rough, and your skin is smooth. When smooth surfaces rub against rough surfaces, the rough surface will do an incredible job in attempting to stop your skin from moving too quickly. The result is a heating or burning feeling that damages your skin to the point that you need a band-aid.
- One thing you probably didn’t know is that forest fires can be caused by friction. We’ve learned in the D.A.R.E. program taught in our elementary and middle schools that forest fires are mainly caused by unattended camp fires or dropped cigarettes. These things are true and are the most common causes of forest fires, but friction can also cause this disaster. Tree branches that swing because of gusts of wind can rub against each other, creating heat. If the heat becomes too much, trees can smoke and catch fire. Dried leaves and other matter can catch fire from a small spark. Even minor cases of everyday friction can cause huge problems in the future.
- If you’ve heard your mom or dad drill a cabinet fixture or heard a construction worker using a jackhammer, you’ll most likely recall the loud noises they make. This is due to friction (surprise!). The drill bit your parents use on the wood has to spin in order to create a small hole for nails or screws. The wood in your cabinet wants to stop the metal from spinning, so the resulting friction will create the loud noises. Jackhammers use metal bits to destroy asphalt surfaces. Once again, the metal-on-asphalt creates friction and loud noises.