[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-665523-105":3,"detail-sidebar-cat-0-en-105":80,"doc-detail-665523-en":130},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":73,"head_meta":75,"extra_data":77,"updated_unix":79},105,"en","free-body-diagrams-newtons-laws","Free-body diagrams - Newton’s Laws","","Lecture notes introducing free-body diagrams and summarizing Newton’s Laws of motion. The first law states that momentum remains constant when no net force acts; the second law presents the force–acceleration relation F = ma; the third law describes equal and opposite action–reaction forces. The notes also emphasize that “laws” are empirical approximations based on idealizations. They discuss the two fundamental force origins in mechanics—gravity and electromagnetism—then derive weight W = mg and its dependence on location, with examples comparing Earth and the Moon.",{"@graph":14,"@context":72},[15,34,55],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/technology/","Technology",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/free-body-diagrams-newtons-laws/665523/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/free-body-diagrams-newtons-laws/665523.png","ImageObject",300,407,{"name":42,"@type":43},"anakgang17","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-30","2026-10-29",true,{"@type":52,"interactionType":53,"userInteractionCount":30},"InteractionCounter",{"@type":54},"ViewAction",{"@type":56,"mainEntity":57},"FAQPage",[58,64,68],{"name":59,"@type":60,"acceptedAnswer":61},"What do Newton’s first, second, and third laws state about motion and forces?","Question",{"text":62,"@type":63},"First law: momentum stays constant when no net force acts. Second law links force to acceleration via F = ma. Third law: forces come in equal magnitude and opposite direction between two interacting objects.","Answer",{"name":65,"@type":60,"acceptedAnswer":66},"Why are Newton’s laws described as approximate rather than absolute rules?",{"text":67,"@type":63},"They are empirical observations that work well within practical idealizations. Real physical quantities like mass vary slightly and matter at very small scales may not follow classical mechanics.",{"name":69,"@type":60,"acceptedAnswer":70},"How are gravity and electromagnetism connected to most mechanical forces?",{"text":71,"@type":63},"Mechanics forces are described as emerging from gravity and electromagnetism. Gravity directly produces weight W = mg near Earth’s surface, while many other forces (such as friction, lift, and drag) are electromagnetic effects in disguise.","https://schema.org",{"og:url":32,"og:type":74,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":76,"canonical":32},"index,follow",{"doc_id":78,"site_id":7},665523,1793304693,{"code":4,"msg":81,"data":82},"success",[83,87,91,95,100,104,109,114,119,122,126],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":84,"show_sort_weight":85,"slug":86},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":88,"show_sort_weight":89,"slug":90},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":92,"show_sort_weight":93,"slug":94},"Exam",70,"exam",{"id":96,"doc_module":4,"doc_module_name":25,"category_name":97,"show_sort_weight":98,"slug":99},5,"Comic",60,"comic",{"id":101,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":102,"slug":103},6,50,"technology",{"id":105,"doc_module":4,"doc_module_name":25,"category_name":106,"show_sort_weight":107,"slug":108},7,"Healthcare",40,"healthcare",{"id":110,"doc_module":4,"doc_module_name":25,"category_name":111,"show_sort_weight":112,"slug":113},8,"Research & Report",30,"research-report",{"id":115,"doc_module":4,"doc_module_name":25,"category_name":116,"show_sort_weight":117,"slug":118},9,"Religion & Spirituality",20,"religion-spirituality",{"id":117,"doc_module":4,"doc_module_name":25,"category_name":120,"show_sort_weight":117,"slug":121},"World Cup","world-cup",{"id":123,"doc_module":4,"doc_module_name":25,"category_name":124,"show_sort_weight":123,"slug":125},10,"Lifestyle","lifestyle",{"id":127,"doc_module":4,"doc_module_name":25,"category_name":128,"show_sort_weight":96,"slug":129},19,"General","general",{"code":4,"msg":81,"data":131},{"doc_id":78,"user_id":132,"nickname":42,"user_avatar":133,"doc_module":4,"category_id":101,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":30,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":110,"language":139,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":12,"update_tm":79,"read_time":117},962090883568,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","Free-body diagrams  \nNewton’s Laws  \nFor this lecture, I shall assume that you have already been introduced to forces and to Newton’s laws of motion, so I shall begin by summarizing them here,  \nNewton’s First Law  \nThe momentum of a mass that is not subject to any forces acting on it remains constant.  \nNewton’s Second Law  \nF  ma (1)  \nNewton’s Third Law  \nAn object that exerts a force on another will experience a force from that other object that is equal in magnitude but opposite in its direction from that which it is exerting.  \nF1 acting on 2  F2 acting on 1 (2)  \nAlthough these are called ‘laws’, they are not absolute rules governing the natural world, but are rather only approximate statements about it. They usually work extremely well for describing most of what occurs in one’s daily experience, as long as one does not ask for too much precision. For example, in the second law, we have treated the mass as though it is a fixed quantity, but that is really just an idealization. The mass of an ordinary brick is not a perfectly defined quantity—a bit of it is worn off as it slides over a rough surface, or it might scrape off and attach some of that surface to itself. And at a subtler level, at every moment the atoms of the brick a sublimating back and forth into the air around it. But if we do not need to be overly finicky about the mass of the brick, it is usually a useful approximation to treat it as though it has a constant, well defined mass.  \nIt is equally important to realize that these laws are empirical observations about what happens in the natural world, instead of being mathematical axioms or definitions. We do not define a force to be something that accelerates masses—a force is supposed to have an independent existence in nature. What these laws tell us is how each of these independent things—forces, masses and accelerations—influence each other. Since physics relies so much on mathematics, it is very tempting to think of these laws as the starting axioms of a mathematical structure. In fact, it is possible to do exactly that and thereby to  \ncreate a beautiful branch of mathematics. However, that mathematics is not the same as the physical world, even though at times that mathematics might provide a useful way for organizing a description of what happens there. But the real physical world is messier than what follows just from Newton’s laws; and in some more extreme circumstances—for example at tiny molecular distancesand smaller—it is described not at all by classical mechanics.  \nSo while it is essential to know how to apply Newton’s laws, as well as other laws that we shall encounter later, it is always a good idea to remember that physics is only a description of the natural world, and one which works in various degrees of idealizations of it. There is nothing wrong with this approach, and it has over history led to a tremendous amount of genuine and profound understanding about the world; without these idealizations—constant masses, simple force laws—it would have been extremely difficult to understand the messy, complicated natural world all at once. After we have understood how one idealized version of nature works, we are then free to add new details and complications to the picture.  \nForces  \nEssentially all of the forces that occur in mechanics are the result of just two basic forces, gravity and electromagnetism. Gravity always appears in a completely undisguised form; that is, when we are speaking of gravity, we are not secretly talking about some other more fundamental force that produces something else that we call gravity. Over the centuries the theory of gravity has grown more subtle, but it remains a basic force of nature, felt by all matter, and so far it still appears to be unconnected with any other force.  \nNear the surface of the earth, gravity produces a very familiar force, the weight of an object. This force is always directed downward, or more correctly toward the center of the earth, and","cbCaikrmxxyYzgHp","https://ap.wps.com/l/cbCaikrmxxyYzgHp","pdf",134159,"English","# Free-body diagrams\n# Newton’s Laws\n## Newton’s First Law\n## Newton’s Second Law\n## Newton’s Third Law\n# Forces\n## Gravity and weight W = mg\n## Electromagnetism and empirical forces\n## Friction as an example","[{\"question\":\"What do Newton’s first, second, and third laws state about motion and forces?\",\"answer\":\"First law: momentum stays constant when no net force acts. Second law links force to acceleration via F = ma. Third law: forces come in equal magnitude and opposite direction between two interacting objects.\"},{\"question\":\"Why are Newton’s laws described as approximate rather than absolute rules?\",\"answer\":\"They are empirical observations that work well within practical idealizations. Real physical quantities like mass vary slightly and matter at very small scales may not follow classical mechanics.\"},{\"question\":\"How are gravity and electromagnetism connected to most mechanical forces?\",\"answer\":\"Mechanics forces are described as emerging from gravity and electromagnetism. Gravity directly produces weight W = mg near Earth’s surface, while many other forces (such as friction, lift, and drag) are electromagnetic effects in disguise.\"}]","Free-body diagrams - Newton’s Laws | PDF"]