Stage 3 Forces and Magnetism Comprehension The Three Laws - Comprehension Pack.pdf

STAGE 3 Unit focus: Forces And Magnetism Text focus: Information Text The Three Laws Forces are all around us. They hold the universe together and mean that humans can go...

STAGE 3 Unit focus: Forces And Magnetism Text focus: Information Text The Three Laws Forces are all around us. They hold the universe together and mean that humans can go about their lives knowing how things will happen. There are lots of different types of forces. They all follow a set of rules that a scientist called Isaac Newton first discovered in 1686. These three rules are known as Newton’s Laws of Motion. They may seem obvious to you, but they explain how every force in the whole universe works. Newton’s First Law The first law describes how a stationary object will act. Stationary means that the object isn’t moving. In scientific terms, it is said to be at rest. It also describes how an object moves. Newton realised that an object will continue to move in the same direction at the same speed until another force stops it. If an object is still, then it won’t move until a force is applied to it. This was really important because it explained how everything worked. When you throw a ball, it should fly forever. Newton’s rule made scientists realise that other forces must be slowing it down. Newton’s Second Law This law is all about mass. Mass is how much stuff something is made of. On Earth, we call this an object’s weight (because gravity is different in space, your weight would be different, but your mass would be the same). This law is really important because it shows how much force is needed to move an object depending on how much mass it has. Not only that, but you can also tell how fast it will accelerate. You can see this in your everyday life. If you kick a football harder, it will go faster. If you kick a heavier football, you will need to kick it harder to make it go as fast. This law is really important because it helps to calculate things like car crashes and is important for scientists to work out how to make things like aeroplanes and rockets work. A ding ro Rea und all resources ©2022 Literacy Shed e um C u r r ic ul Th http://www.literacyshedplus.com Newton’s Third Law This is perhaps the most famous law. Newton said for every action, there is an equal and opposite reaction. This means that all forces act in pairs. For instance, when you jump, you create a force moving you upwards. Gravity is the force pulling you down. If the forces are the same or balanced, then nothing happens. When you put something down on a level table, all of the forces are balanced, so it doesn’t move. If you put a ball on a slope, then gravity will be stronger than the other forces, and it will roll. When you pick something up, your lifting force is stronger than the force of gravity. Heavier objects need more force (remember the Second Law), so it is harder to overcome gravity and lift them. RETRIEVAL FOCUS 1. When did Newton create his three laws? 2. Which law tells you that that heavier objects need more force to move them? 3. If you throw a tennis ball harder, you would expect it to move ___________. 4. True or false: sometimes, an object can move without any force being applied to it. 5. Which force pulls you down when you jump on a trampoline? VIPERS QUESTIONS S Give an example of the Second Law that isn’t given in the text. S Why would your weight be different on another planet? V Find and copy a word that describes an object that is at rest. V If something is in a pair, how many are there? P How might you experience forces differently on the moon? all resources ©2022 Literacy Shed http://www.literacyshedplus.com