Stage 3 Forces and Magnetism Comprehension Friction - Comprehension Pack.pdf

STAGE 3 Unit focus: Forces And Magnetism Text focus: Information Text Friction We need friction to do anything. It is a resistive force. That means that it acts against othe...

STAGE 3 Unit focus: Forces And Magnetism Text focus: Information Text Friction We need friction to do anything. It is a resistive force. That means that it acts against other forces. Friction is generated whenever two objects rub against each other. Different objects create different amounts of friction. If something has a large surface area, then it creates more friction. Rough objects have tiny lumps and bumps that increase their surface area. This means that rougher materials usually create more friction. You will have experienced lots of different types of friction. It can be really useful. When you pick up a pencil or a cup, you rely on the friction between it and your hand. If there wasn’t enough friction, it would slip and drop. That’s why it’s harder to pick up wet objects - the water reduces the friction. Friction can also be bad. When you fall over and graze your knee, it is friction that causes the graze. Did you know that your body changes to help with friction? When you spend too long in the water, your fingertips wrinkle. Scientists believe that we have evolved like this because it makes the surface area of our fingers larger. This makes it easier to grip things when we have wet hands. Amazing or what? Another type of friction is air resistance. Air resistance fights against anything moving through the air. It’s what slows down a ball that you kick and why you can feel the wind blowing against you. Air resistance also depends on the surface area of an object. If you throw a tennis ball and a football with the same force, the tennis ball will go further. This is because it is smaller, so there is less surface area for the air resistance. Friction creates heat energy. This can be frustrating because lots of the energy that goes into moving the object is then lost as heat. When you rub your hands together quickly, you will feel that they get hot. The same thing happens A with car tyres on the road. It also happens with car brakes. ding ro Rea und all resources ©2022 Literacy Shed e um C u r r ic ul Th http://www.literacyshedplus.com When a car brakes, metal pads press against the wheels to slow them down. This loses a lot of energy as heat. Modern hybrid cars make use of this energy. They are able to take the energy from the friction and convert it into electricity for the car’s battery. This means that they can recharge as you drive. Friction can also generate static electricity. If you’ve ever rubbed a balloon on your jumper and stuck it to the wall, you’ve seen this in action. There is another type of friction called fluid friction. This slows objects down as they move through fluids. This is really important in places like water slides. Without it, you would travel down the slide at dangerous speeds. Unfortunately, it is also what causes such a sting when you belly-flop into a pool! RETRIEVAL FOCUS 1. Objects with a __________ surface area create more friction. 2. You can feel air resistance on a __________ day. 3. Friction is often wasted as _________ energy. 4. Which modern technology makes the most of wasted energy? 5. Where might you have experienced fluid friction? VIPERS QUESTIONS V What is the root word of resistive? S How does friction help you in your day to day life? S How have we evolved to make the most of friction? V Find and copy a phrase that describes how much of something is acted on by a force. E Why has the author included examples of the different types of friction? all resources ©2022 Literacy Shed http://www.literacyshedplus.com