`); let searchUrl = `/search/`; history.forEach((elem) => { prevsearch.find('#prevsearch-options').append(`
${elem} `); }); } $('#search-pretype-options').empty(); $('#search-pretype-options').append(prevsearch); let prevbooks = $(false); [ {title:"Recently Opened Textbooks", books:previous_books}, {title:"Recommended Textbooks", books:recommended_books} ].forEach((book_segment) => { if (Array.isArray(book_segment.books) && book_segment.books.length>0 && nsegments<2) { nsegments+=1; prevbooks = $(`
${book_segment.title} `); let searchUrl = "/books/xxx/"; book_segment.books.forEach((elem) => { prevbooks.find('#prevbooks-options'+nsegments.toString()).append(`
${elem.title} ${ordinal(elem.edition)} ${elem.author} `); }); } $('#search-pretype-options').append(prevbooks); }); } function anon_pretype() { let prebooks = null; try { prebooks = JSON.parse(localStorage.getItem('PRETYPE_BOOKS_ANON')); }catch(e) {} if ('previous_books' in prebooks && 'recommended_books' in prebooks) { previous_books = prebooks.previous_books; recommended_books = prebooks.recommended_books; if (typeof PREVBOOKS !== 'undefined' && Array.isArray(PREVBOOKS)) { new_prevbooks = PREVBOOKS; previous_books.forEach(elem => { for (let i = 0; i < new_prevbooks.length; i++) { if (elem.id == new_prevbooks[i].id) { return; } } new_prevbooks.push(elem); }); new_prevbooks = new_prevbooks.slice(0,3); previous_books = new_prevbooks; } if (typeof RECBOOKS !== 'undefined' && Array.isArray(RECBOOKS)) { new_recbooks = RECBOOKS; for (let j = 0; j < new_recbooks.length; j++) { new_recbooks[j].viewed_at = new Date(); } let insert = true; for (let i=0; i < recommended_books.length; i++){ for (let j = 0; j < new_recbooks.length; j++) { if (recommended_books[i].id == new_recbooks[j].id) { insert = false; } } if (insert){ new_recbooks.push(recommended_books[i]); } } new_recbooks.sort((a,b)=>{ adate = new Date(2000, 0, 1); bdate = new Date(2000, 0, 1); if ('viewed_at' in a) {adate = new Date(a.viewed_at);} if ('viewed_at' in b) {bdate = new Date(b.viewed_at);} // 100000000: instead of just erasing the suggestions from previous week, // we just move them to the back of the queue acurweek = ((new Date()).getDate()-adate.getDate()>7)?0:100000000; bcurweek = ((new Date()).getDate()-bdate.getDate()>7)?0:100000000; aviews = 0; bviews = 0; if ('views' in a) {aviews = acurweek+a.views;} if ('views' in b) {bviews = bcurweek+b.views;} return bviews - aviews; }); new_recbooks = new_recbooks.slice(0,3); recommended_books = new_recbooks; } localStorage.setItem('PRETYPE_BOOKS_ANON', JSON.stringify({ previous_books: previous_books, recommended_books: recommended_books })); build_popup(); } } var whiletyping_search_object = null; var whiletyping_search = { books: [], curriculum: [], topics: [] } var single_whiletyping_ajax_promise = null; var whiletyping_database_initial_burst = 0; //number of consecutive calls, after 3 we start the 1 per 5 min calls function get_whiletyping_database() { //gets the database from the server. // 1. by validating against a local database value we confirm that the framework is working and // reduce the ammount of continuous calls produced by errors to 1 per 5 minutes. return localforage.getItem('whiletyping_last_attempt').then(function(value) { if ( value==null || (new Date()) - (new Date(value)) > 1000*60*5 || (whiletyping_database_initial_burst < 3) ) { localforage.setItem('whiletyping_last_attempt', (new Date()).getTime()); // 2. Make an ajax call to the server and get the search database. let databaseUrl = `/search/whiletype_database/`; let resp = single_whiletyping_ajax_promise; if (resp === null) { whiletyping_database_initial_burst = whiletyping_database_initial_burst + 1; single_whiletyping_ajax_promise = resp = new Promise((resolve, reject) => { $.ajax({ url: databaseUrl, type: 'POST', data:{csrfmiddlewaretoken: "8jcrkqWuoO7yApECHrd4qPBc7vJQfxehnkp07PYh4UNCrmMbCVF9JNSKWcJN6bWk"}, success: function (data) { // 3. verify that the elements of the database exist and are arrays if ( ('books' in data) && ('curriculum' in data) && ('topics' in data) && Array.isArray(data.books) && Array.isArray(data.curriculum) && Array.isArray(data.topics)) { localforage.setItem('whiletyping_last_success', (new Date()).getTime()); localforage.setItem('whiletyping_database', data); resolve(data); } }, error: function (error) { console.log(error); resolve(null); }, complete: function (data) { single_whiletyping_ajax_promise = null; } }) }); } return resp; } return Promise.resolve(null); }).catch(function(err) { console.log(err); return Promise.resolve(null); }); } function get_whiletyping_search_object() { // gets the fuse objects that will be in charge of the search if (whiletyping_search_object){ return Promise.resolve(whiletyping_search_object); } database_promise = localforage.getItem('whiletyping_database').then(function(database) { return localforage.getItem('whiletyping_last_success').then(function(last_success) { if (database==null || (new Date()) - (new Date(last_success)) > 1000*60*60*24*30 || (new Date('2023-04-25T00:00:00')) - (new Date(last_success)) > 0) { // New database update return get_whiletyping_database().then(function(new_database) { if (new_database) { database = new_database; } return database; }); } else { return Promise.resolve(database); } }); }); return database_promise.then(function(database) { if (database) { const options = { isCaseSensitive: false, includeScore: true, shouldSort: true, // includeMatches: false, // findAllMatches: false, // minMatchCharLength: 1, // location: 0, threshold: 0.2, // distance: 100, // useExtendedSearch: false, ignoreLocation: true, // ignoreFieldNorm: false, // fieldNormWeight: 1, keys: [ "title" ] }; let curriculum_index={}; let topics_index={}; database.curriculum.forEach(c => curriculum_index[c.id]=c); database.topics.forEach(t => topics_index[t.id]=t); for (j=0; j
(b.item.view_count || 0) - (a.item.view_count || 0)); whiletyping_search = {books: [], curriculum: [], topics: []}; const MAX_BOOKS=3; const MAX_COURSES=4; const MAX_TOPICS=6; let curriculum_titles = new Set(); let topics_titles = new Set(); add_without_repetition = (params)=>{ // insert items from elems into array checking that array is max size // and no title duplicates for (var i = 0; i=params.max) {break;} if (!params.titles.has(params.elems[i].item.title)){ params.titles.add(params.elems[i].item.title); params.array.push(params.elems[i].item); } } } add_without_repetition({ max: MAX_COURSES, titles: curriculum_titles, elems: curriculum, array: whiletyping_search.curriculum }); add_without_repetition({ max: MAX_TOPICS, titles: topics_titles, elems: topics, array: whiletyping_search.topics }); for (var i = 0; i=MAX_BOOKS) {break;} book = books[i].item; whiletyping_search.books.push(book); add_without_repetition({ max: MAX_COURSES, titles: curriculum_titles, elems: book.curriculum, array: whiletyping_search.curriculum }); add_without_repetition({ max: MAX_TOPICS, titles: topics_titles, elems: book.topics, array: whiletyping_search.topics }); } return true; } else { return false; } }); } function build_solutions() { if (Array.isArray(solution_search_result)) { const viewAllHTML = userSubscribed ? `View All` : ''; var solutions_section = $(` Solutions ${viewAllHTML} `); let questionUrl = "/questions/xxx/"; let askUrl = "/ask/question/xxx/"; solution_search_result.forEach((elem) => { let url = ('course' in elem)?askUrl:questionUrl; let solution_type = ('course' in elem)?'ask':'question'; let subtitle = ('course' in elem)?(elem.course??""):(elem.book ?? "")+" "+(elem.chapter?"Chapter "+elem.chapter:""); solutions_section.find('#whiletyping-solutions').append(` ${elem.text} ${subtitle} `); }); $('#search-solution-options').empty(); if (Array.isArray(solution_search_result) && solution_search_result.length>0){ $('#search-solution-options').append(solutions_section); } MathJax.Hub.Queue(["Typeset", MathJax.Hub, document.getElementById('search-solution-options')]); } } function build_whiletyping() { $('#search-pretype-options').empty(); $('#search-pretype-options').append($('#search-solution-options').html()); if (Array.isArray(whiletyping_search.books) && whiletyping_search.books.length>0) { var books_section = $(` Textbooks View All `); let searchUrl = "/books/xxx/"; whiletyping_search.books.forEach((elem) => { books_section.find('#whiletyping-books').append(` ${elem.title} ${ordinal(elem.edition)} ${elem.author} `); }); } $('#search-pretype-options').append(books_section); } function build_popup(first_time = false) { if ($('#search-text').val()=='') { build_pretype(); if (first_time) { do_whiletyping_search(); } } else { solution_search(); do_whiletyping_search().then((success) => { if (success) { build_whiletyping(); } else { build_pretype(); } }).catch((err) => { console.log(err); build_pretype(); }); } } var search_text_out = true; var search_popup_out = true; const is_login = false; function pretype_setup() { $('#search-text').focusin(function() { $('#search-popup').addClass('show'); resize_popup(); search_text_out = false; }); $( window ).resize(function() { resize_popup(); }); $('#search-text').focusout(() => { search_text_out = true; if (search_text_out && search_popup_out) { $('#search-popup').removeClass('show'); } }); $('#search-popup').mouseenter(() => { search_popup_out = false; }); $('#search-popup').mouseleave(() => { search_popup_out = true; if (search_text_out && search_popup_out) { $('#search-popup').removeClass('show'); } }); $('#search-text').on("keyup", delay(() => { build_popup(); }, 200)); build_popup(true); let prevbookUrl = `/search/pretype_books/`; if (is_login) { $.ajax({ url: prevbookUrl, method: 'POST', data:{csrfmiddlewaretoken: "8jcrkqWuoO7yApECHrd4qPBc7vJQfxehnkp07PYh4UNCrmMbCVF9JNSKWcJN6bWk"}, success: function(response){ previous_books = response.previous_books; recommended_books = response.recommended_books; build_popup(); }, error: function(response){ console.log(response); } }); } else { let prebooks = null; try { prebooks = JSON.parse(localStorage.getItem('PRETYPE_BOOKS_ANON')); }catch(e) {} if (prebooks && 'previous_books' in prebooks && 'recommended_books' in prebooks) { anon_pretype(); } else { $.ajax({ url: prevbookUrl, method: 'POST', data:{csrfmiddlewaretoken: "8jcrkqWuoO7yApECHrd4qPBc7vJQfxehnkp07PYh4UNCrmMbCVF9JNSKWcJN6bWk"}, success: function(response){ previous_books = response.previous_books; recommended_books = response.recommended_books; build_popup(); }, error: function(response){ console.log(response); } }); } } } $( document ).ready(pretype_setup); $( document ).ready(function(){ $('#search-popup').on('click', '.search-view-item', function(e) { e.preventDefault(); let autoCompleteSearchViewUrl = `/search/autocomplete_search_view/`; let objectUrl = $(this).attr('href'); let selectedId = $(this).data('objid'); let searchResults = []; $("#whiletyping-solutions").find("a").each(function() { let is_selected = selectedId === $(this).data('objid'); searchResults.push({ objectId: $(this).data('objid'), contentType: $(this).data('contenttype'), category: $(this).data('category'), selected: is_selected }); }); $("#whiletyping-books").find("a").each(function() { let is_selected = selectedId === $(this).data('objid'); searchResults.push({ objectId: $(this).data('objid'), contentType: $(this).data('contenttype'), category: $(this).data('category'), selected: is_selected }); }); $.ajax({ url: autoCompleteSearchViewUrl, method: 'POST', data:{ csrfmiddlewaretoken: "8jcrkqWuoO7yApECHrd4qPBc7vJQfxehnkp07PYh4UNCrmMbCVF9JNSKWcJN6bWk", query: $('#search-text').val(), searchObjects: JSON.stringify(searchResults) }, dataType: 'json', complete: function(data){ window.location.href = objectUrl; } }); }); });
FAQs
Describe why your velocity changes when you ride a Ferris wheel even if the wheel turns at a constant speed. As the Ferris wheel turns, you are moving in a different direction at each instant of time. Since the direction changes, the velocity changes.
What is a Ferris wheel with a radius of 15m is rotating at a rate of one revolution every two minutes? ›
Here, the angular speed is 1 revolution every 2 minutes or 2π rad/2min = π rad/min. Therefore, The linear speed is π * 15 = 15π m/min approximately. The vertical speed at this point would be linear speed * sin(53) which equals approximately 11.8 m/min.
Does a person riding a Ferris wheel motion in a circle at a constant speed accelerate explain? ›
Acceleration is defined as the rate of change, with respect to time, of velocity. Velocity is defined as having speed and direction. The Ferris wheel is rotating and so a point on it changes direction continuously and so has acceleration although its speed is constant.
At what rpm is a Ferris wheel turning when the rider feels weightlessness or zero gravity every time the rider is at the topmost part of the wheel 9 m in radius? ›
At what rpm is the ferris wheel turning when the riders feel weightlessness or zero gravity every time each rider is at the topmost part of the wheel 9 m in radius. Correct answer is 9.97 rpm.
How does physics apply to Ferris wheel? ›
As you travel around the center of the Ferris wheel, the force of gravity, normal force and centripetal force all are pushing and pulling against you. As you approach the bottom of the ride, you feel “heavier” because the normal force of your seat has to increase, and the centripetal force is now pulling you up.
How can a passenger on a Ferris wheel be revolving at the same speed yet still be accelerating? ›
Yes. Just moving in a circular motion (constantly changing direction) but traveling at the same speed (magnitude of velocity) would be an accelerated motion. The direction of this acceleration is pointed towards the center of the circle based on the curvature of the turn.
How do you find the speed of a Ferris wheel? ›
For any wheel it takes 2π radians or 360o to make one revolution. The angular speed is then ω = 2π / t, with t = the time it takes to make one revolution. For the Ferris wheel the angular speed is ω = 2π / 75 rads/s.
Is the radius of a Ferris wheel the amplitude? ›
Then your maximum height above the axis is one radius above 0 , and your minimum height is radius below 0 You can easily derive the 'amplitude' of a Ferris wheel by taking half de diameter of the wheel. This height we call amplitude . In other words: the amplitude is half the diameter (=the radius) of the circle.
What is radius times rotational speed? ›
Look back at the formula for angular speed. Substituting gives the following relationship between linear and angular speed: v = r ω . So the linear speed is equal to the radius times the angular speed. Remember in a unit circle the radius is 1 unit, so in this case the linear speed is the same as the angular speed.
What is the Ferris wheel theory? ›
In a Ferris wheel, forces are not balanced. Objects that have circular motion have something called “centripetal force”. Centripetal is a word meaning “centre seeking.” The centripetal force always points to the centre of the circle. Ferris wheel physics is directly related to centripetal acceleration.
Why does it seem that wheels go backwards when they go forward? To put it in simple terms, the wheels spin faster than our eyes can see. We see at a certain number of frames per second, and wheels spin too fast for us to see every single moment of the spin.
Does a rider feel heavier or lighter at the bottom of a Ferris wheel ride? ›
At the bottom of the circle centripetal acceleration, which always points towards the center of the circle, is pointing directly up. F2=m(g+a). At the bottom of the Ferris wheel the passengers experience 1.5g and they feel heavier.
How many revolutions per minute would a 15 m diameter Ferris wheel have? ›
In summary, a 15m diameter Ferris wheel would complete approximately 1.5 revolutions per minute. This is based on the standard calculation for the circumference of a circle, where the distance traveled in one revolution is equal to the diameter of the circle multiplied by pi (3.14).
What minimum speed would a 15 m diameter Ferris wheel need to make for the passenger to feel weightless at the topmost point? ›
Expert-Verified Answer
A 15 m diameter Ferris wheel would need to make approximately 1.75 revolutions per minute for the passengers to feel weightless at the topmost portion of the trip.
Why does velocity happen when going in a circle even if you are going the same speed? ›
The simplest case of circular motion is uniform circular motion, where an object travels a circular path at a constant speed. Note that, unlike speed, the linear velocity of an object in circular motion is constantly changing because it is always changing direction.
Is a Ferris wheel turning at a constant speed accelerating? ›
To find the acceleration of an object moving in a straight line, you must calculate the change in [distance] during each unit of time. A Ferris wheel turning at a constant speed of 5 m/s [is not] accelerating. An airplane is flying west at 200 km/h. Two hours later, it is flying west at 300 km/h.
Does a Ferris wheel have constant velocity? ›
A typical Ferris wheel rotates at a constant speed (unless stopping to let passengers off). But velocity is speed with a direction vector attached to it, so velocity is changing every second. Your bodies' “apparent” weight varies depending on the place you are on the ride.
