![]() ![]() Here you will find one of the largest collections of different games. On our site you can play all online games for free. Please note that our site is called Friv2Online and we have nothing to do with the original site with Friv games. Princess Easter Hurly-Burly Highschool Mean Girls From Nerd To Fab: Prom Edition Princess E-girl Fashion Pony Dress Up Harlequin is Preparing an April Fools Rally Princesses Back to School Goldie Wedding Proposal HighSchool Cheerleader Dressup Miss Charming Unicorn Hairstyle Kawaii High School Teacher Dress Up Barbie with Twins Cinderella in Modernland Morning Mix-up - The PowerPuff Girls Princess Winter Style Unordinary Week - Play The PowerPuff Girls Shopping Outfits Ellie Fashion Fever Romantic Anime Couples Dress Up Princess Collective Wedding Anime Fantasy RPG Dress Up Red Carpet Dress Up Girls My Sister's Perfect Wedding Top Model Dress Up Anime Princess Dress Up Dress up Games for Girls Land vs Sea: Moana vs Elsa Anime Kawaii Dress Up Soft Girl Aesthetic Anime Kawaii School Girls Dress Up Brilliant Popstar Girls Dress Up Glam Girls Dress Up Glam Dress Up Chibi Fighter Dress Up Game Cool Arabian Princess Dress Up Anime Girl Fashion Dress Up & Makeup Unicorn Dress Up Girls Monster High Beauty Shop Game Super Doll Sisters Transform Gymnastics Dress UpĬompetition in the world of online games is very high and the leaders among many are the games Friv, Poki, Y8 and Kizi. ![]() Princess e-Girl vs Soft Girl Princess Easter Hurly-Burly Highschool Mean Girls From Nerd To Fab: Prom Edition Princess E-girl Fashion Pony Dress Up Princess Cupcake Harlequin is Preparing an April Fools Rally Princesses Back to School Goldie Wedding Proposal HighSchool Cheerleader Dressup Miss Charming Unicorn Hairstyle Kawaii High School Teacher Dress Up Vsco Girl Fashion Barbie with Twins Cinderella in Modernland Morning Mix-up - The PowerPuff Girls Smashing Bots - PowerPuff Girls Princess Winter Style Unordinary Week - Play The PowerPuff Girls Ellie Fashion Fever Romantic Anime Couples Dress Up Princess Collective Wedding Anime Fantasy RPG Dress Up Red Carpet Dress Up Girls My Sister's Perfect Wedding Top Model Dress Up Anime Princess Dress Up Dress up Games for Girls Land vs Sea: Moana vs Elsa Princess Salon Frozen Party Anime Kawaii Dress Up Soft Girl Aesthetic Anime Kawaii School Girls Dress Up Brilliant Popstar Girls Dress Up Glam Girls Dress Up Baby Hazel Flower Girl Glam Dress Up Chibi Fighter Dress Up Game Cool Arabian Princess Dress Up Agent P: Rebel Spy Hypno Bliss - PowerPuff Girls Fireboy and Watergirl 5: Elements Bus & Subway Runner Table Tennis Ultimate Tournament Spider Man: Mysterio Rush Gumball Strike Ultimate Bowling Hero Time - Ben 10 Toon Cup 2019 Batman Shadow Combat Cheese Swipe Finn & Bones - Adventure Time Scooby-Doo: Mystery Chase Star Wars Rebels: Special Ops Frozen Rush Fireboy and Watergirl 4: The Crystal Temple Rust Bucket Rescue - Ben 10 One on One - Teen Titans Go! Tom and Jerry: Dont Make A Mess Penalty Power - Ben 10 Unikitty Save the Kingdom Finn & Bones - Adventure Time Zombie Hunters Arena Ben 10 World Rescue Gumball Water Sons Black Panther: Jungle Pursuit Alien Rush - Ben 10 Captain America: Shield Strike Tower Lockdown - Teen Titans Go! Ben 10 Run Star vs the Dungeon of Evil Titanic Heartbreak - Teen Titans Go! Slash of Justice - Teen Titans Go! Upgrade Chasers - Ben 10 The Night Begins to Shine - Teen Titans Go! Escape Route - Ben 10 Power Tower - Teen Titans Go! Sky Streaker - Gumball Robin VS See-more - Teen Titans Go! Guardians of the Galaxy: Legendary Relics
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![]() Halo 3: Generally considered to be the culmination of Bungie's vision, and the perfect conclusion to the Halo series, Halo 3 is truly one of the greatest games ever made.While multiplayer was present in Halo: Combat Evolved, Halo 2's become a phenomenon, with iconic maps that are still used in modern Halo offerings. That's without even mentioning Halo 2's multiplayer, which is credited with popularizing online console gaming, now an integral aspect of the industry. Throw in the ability to dual-wield weapons and hijack vehicles, and Halo 2 is one of the best Xbox games ever created, easily deserving a top spot on this list. ![]() The plot feels more cinematic and larger in scope, the combat mechanics feel more fleshed-out, and each level offers a bold and beautiful new environment. With more weapons, vehicles, and enemies, Halo 2 is a sequel done very right, taking the essence of the first game, and expanding on it in almost every way. Halo 2: Though its dual protagonist approach is a controversial one, and the ending is very, very rushed, Halo 2 remains one of the best games in the franchise.Open-ended levels, high production value, a unique world and premise, and a decent amount of enemy variety all keep Halo: Combat Evolved an experience worth playing even over two decades later. Aside from beginning the legacy, Halo: Combat Evolved is a great game in its own right. While its level design gets very repetitive toward the game's latter half, the visuals are a little dated, and the multiplayer isn't the best in the series, Halo: Combat Evolved is a ridiculously great first outing, and without it, some of the greatest games of all time wouldn't have been made. Halo Combat Evolved: The one that started it all, there's no denying that Halo: Combat Evolved is a true S-Tier title.RELATED: There Should be More Halo Stories Without Master Chief S-Tier At its best, Halo is a groundbreaking franchise that revolutionized console first-person shooters, and at its worst, Halo can be an over-hyped, confusing experience that still offers solid gameplay but lacks any of the charm the franchise is known for. While the original Halo trilogy is widely considered to be one of the best in gaming, the various spinoffs and sequels that have followed its release have been a bit of a mixed bag. Its gameplay has also remained at the cutting edge of the industry. With a mainline series that sees the Spartan supersoldier John-117 - also known as Master Chief - defending Earth and the rest of humanity from alien Covenant and Flood forces, and several spin-offs fleshing out the history of this conflict, Halo is one of the deepest gaming franchises around. The series that almost single-handedly made the Xbox a success, Halo is still regarded as one of the greatest Sci-Fi gaming franchises of all time. ![]() Notice to Students RE: Professional Licensure and CertificationĬalifornia State University programs for professions that require licensure or certification are intended to prepare the student for California licensure and certification requirements. In addition to California State University, Sacramento's full accreditation by the Western Association of Schools and Colleges, the Bachelor of Science, Master of Business, and Master of Science are also individually accredited by the AACSB Internationally Association to Advance Collegiate Schools of Business. Minor in Real Estate and Land Use Affairs Minor in Management of Human Resources and Organizational Behavior Degree ProgramsīS in Business (Management of Human Resources and Organizational Behavior)īS in Business (Management Information System) Note: The use of the word “business” throughout this section refers to courses designated as Accountancy (ACCY), Accounting Information Systems (AIS), Decision Sciences (DS), Entrepreneurship (ENTR), Finance (FIN), General Management (GM), Human Resources/Organizational Behavior (HROB), International Business (IBUS), Management (MGMT), Management Information Science (MIS), Marketing (MKTG), Operations Management (OPM). A Minor in Business is valuable to the student majoring in another area who wishes to supplement his/her knowledge with a business background. The College also offers Minors in Business, Management of Human Resources and Organizational Behavior, Marketing, Real Estate and Land Use Affairs, and Risk Management and Insurance. For information about program options, please visit our website at: Undergraduate Programs | Sacramento State (). For example, students may elect dual concentrations such as General Management and Management of Human Resources and Organizational Behavior. Students who wish a more customized program may elect to complete the requirements for additional concentrations as well. The structure of the General Management concentration also provides an overlap with the other concentrations, thus making changes in focus possible. Students who are uncertain about which concentration to choose are encouraged to select the General Management concentration, as it is the most comprehensive. All students must choose a concentration to complete their requirements for the baccalaureate degree. Additionally, the COB's Business Honors program provides an alternative path to its most capable students to prepare them for management opportunities. The Bachelor of Science program offers students a choice of 9 concentrations by which they may focus their goals. The College of Business offers a broad professional education in Business. Sp Ed, Rehab, School Psychology & Deaf Studies (EDS).Recreation, Parks, and Tourism Administration (RPTA). ![]() International Masters in Business Administration (IMBA).Human Resources/Organizational Behavior (HROB).Fashion Merchandising and Management (FASH).Family Studies and Human Development (FSHD). ![]()
![]() FAQ & AnswersĪ: It is likely that your dog stepped on a bee due to curiosity, poor vision or balance, or unfamiliar surroundings. Additionally, if you notice any signs of allergic reaction such as vomiting or difficulty breathing after they got stung, seek medical attention right away. The first thing you should do is check if there are any stings present on their body and take necessary measures such as washing the affected area with soap and water or applying hydrocortisone cream if needed. ![]() If your pup does step on a bee, assess the situation immediately and take steps to ensure their safety. What Should You Do If Your Dog Steps On A Bee? Additionally, avoid wearing strong scents such as perfume or cologne when outside as this could attract bees towards you and your pup. If you notice any bees nearby, discourage your dog from going near them and guide them away from that area if possible. When taking your pup for a walk or playing in the park, it is important to keep an eye out for any bee activity in the area. Tips To Reduce Risk Of Dog Stepping On Bees Additionally, ensure that your pup is up-to-date on all vaccinations and flea medication to reduce the risk of them getting stung or infected by bees. If there are any visible signs of bee activity, it is best to avoid that area altogether. Preparations Before Letting Dogs Outdoorsīefore letting your dog out in an unfamiliar environment, it is important to check for beehives or nests that may be present in the area. In order to prevent dogs from accidentally stepping on bees, it is important to understand the risks associated with them and take the necessary precautions. Dogs may be unaware of the potential dangers of certain insects, like bees, and their interaction with them can cause serious health problems. Why Did Amber Say Her Dog Stepped on a Bee?Īmber recently said that her dog stepped on a bee, and it’s understandable why she would be worried. It is important for pet owners to monitor their pets closely for any changes in their condition after they have stepped on an insect such as bees since these stings can cause painful reactions that need immediate medical attention if not treated properly. Why Did Amber Say Her Dog Stepped On A Bee?Īmber might have noticed her dog showing signs of discomfort after stepping on a bee such as swelling, redness, itching or burning sensation around the sting site which prompted her to seek help from her veterinarian. If you notice any signs of itching or burning sensation in your pet after they have stepped on a bee, it is important to seek veterinary care immediately as this could be an indication of an allergic reaction that needs to be treated promptly. In some cases, these symptoms can last for several days and even weeks depending on how sensitive your pet is to insect stings. This itching or burning sensation can range from mild to severe depending on the severity of the sting and if your pet has an allergic reaction to the venom injected by the bee. Itching or burning sensation around the sting site can also occur when a dog steps on a bee. If your dog has stepped on a bee and you notice any signs of redness or discomfort, it is important to monitor them closely for any changes in their condition and seek veterinary care as needed. In some cases, additional symptoms such as itching may also occur. This redness may be accompanied by pain and tenderness in the area. Redness around the sting site is another common symptom that can occur when a dog steps on a bee. If the swelling is severe or does not subside after a few hours, it is important to seek veterinary care immediately as it may be an indication of an allergic reaction or infection. In some cases, the swelling may be accompanied by itching or burning sensation. When a bee stings a dog, it injects venom into their skin, which can cause swelling and redness at the site of the sting. Swellingĭogs are prone to swelling due to a number of reasons, including insect bites, infections, allergies and even contact with irritants. She quickly acted to remove the bee from her dog’s paw before any further damage was done. Amber knew that if the bee’s stinger had gone into her dog’s paw, it could have caused serious pain and injury. Amber noticed her dog start to act strangely, and when she looked closer, she saw that the dog had stepped on a bee. Amber said her dog stepped on a bee because the bee was in her backyard. ![]() (Jason Getz/Atlanta Journal-Constitution via AP, Pool, File)Īttorneys who have worked alongside McAfee, who took the bench just this year, say his demeanor and years of work as a prosecutor have prepared him for heightened pressure. But the challenge facing Fulton County Judge Scott McAfee in Georgia is unlike any of the others. Past high-profile trials suggest additional scrutiny and stress for the four judges overseeing the indictments against former President Donald Trump. And the trials will play out in a battleground state that Trump narrowly lost in 2020.įILE- Attorney Scott Grubman, who is defending Kenneth Chesebro, argues before Fulton County Superior Judge Scott McAfee in Atlanta on Wednesday, Sept. He is presiding over a sprawling indictment with 19 defendants, among them other prominent figures including former New York Mayor Rudy Giuliani and Trump White House chief of staff Mark Meadows. For one, he is the only judge so far to allow television cameras in the courtroom to broadcast hearings and any trials. “When you’re in a high-profile trial, you feel the stress, you feel the pressure even if you’re not reading the papers,” he told an audience of judges last year at The National Judicial College in Reno, Nevada.Ĭahill’s experience provides a glimpse of the additional scrutiny and strain that await the four judges overseeing the criminal cases against former President Donald Trump.īut the challenge facing Fulton County Judge Scott McAfee in Georgia is unlike any of the others. Outside, the nation waited nervously for the outcome of a slaying that galvanized the movement for racial justice. We are offering a limited number of hardcover copies.ATLANTA (AP) - Judge Peter Cahill hardly slept during the six weeks he presided over the murder trial of Minneapolis police officer Derek Chauvin for killing George Floyd.Ĭameras in the courtroom broadcast the veteran Minnesota judge’s every word to a global audience. ![]() You can order your 128-page commemorative book by visiting or by calling 1-80 between 10 a.m. Working with Triumph Books, we’re celebrating UGA’s national championship with an exclusive book. To show our appreciation, a copy of the 16-page souvenir section that goes on sale Wednesday will be included in the Wednesday newspaper delivered to your home.īeginning Tuesday morning, we will be selling copies of each of these collectible editions at the lobby of our printing plant at 6455 Best Friend Rd. If you’re a subscriber, we want to thank you for supporting our journalism. Early Wednesday morning, a bonus 16-page section will be available wherever you buy your weekday copy of The Atlanta Journal-Constitution. Through a partnership with That’s Great News, we’re also offering some of these keepsakes in commemorative acrylic and wooden plaques so that they can be proudly displayed.Įarly Tuesday morning, our first of two souvenir sections will be available at Ingles, Kroger, Publix, QT, RaceTrac and select Circle K locations throughout the metropolitan area. You can purchase copies of all our special editions early Tuesday morning at ajc.com/dawgsnews. To help you savor this sweet victory for years to come, we’ve produced a series of collectible editions that make the perfect gift for you or the Dawgs fan in your life. No one has covered the Dawgs like we have. ![]() ![]() ("Steve's salary after deductions = " + hashMap. HashMap.put("Steve", new Integer(deductions - 3000)) Int deductions = ((Integer)hashMap.get("Steve")).intValue() ("Amy's salary after bonus = " + hashMap.get("Amy")) HashMap.put("Amy", new Integer(bonus + 5000)) Int bonus = ((Integer)hashMap.get("Amy")).intValue() ("Size of IdentintyHashMap: "+hashMap.size()) Map.Entry map = (Map.Entry)iterator.next() If you try to insert the duplicate key, it will replace the element of the corresponding key. HashMap.put("Nathan", new Integer(25000)) Java HashMap class implements the Map interface which allows us to store key and value pair, where keys should be unique. ![]() HashMap.put("Steve", new Integer(23000)) HashMap.put("Jacob", new Integer(45000)) HashMap.put("Katie", new Integer(30000)) Let us see another example − import java.util.* This constructor initializes both the capacity and fill ratio of the hash map by using its arguments. This constructor initializes the capacity of the hash map to the given integer value, capacity. Both classes provide similar functionality, but there are also small differences, which we’ll explore in this tutorial. The HashMap is the second implementation, which was introduced in JDK 1.2. This constructor initializes the hash map by using the elements of the given Map object m. Hashtable is the oldest implementation of a hash table data structure in Java. This constructor constructs a default HashMap. This allows the execution time of basic operations, such as get( ) and put( ), to remain constant even for large sets.įollowing is the list of constructors supported by the HashMap class. The HashMap class uses a hashtable to implement the Map interface. ![]() Once you have unarchived the file(s), you should be able to read them with your ebook software. These files are also in archive format, so you will need to again use an un-archiving program (such as 7zip) to unarchive the compressed file. Accept the file and save it into a convenient location. Paste the copied string back into Hexchat entry bar and then wait until you get a prompt that the file is available for downloading. !pizda Jules Verne - From The Earth To The Moon And, Round The Moon.epub Then right click on the highlighted section and use your copy function to copy it to the clipboard. To download a title, highlight the name of the file provider and the complete file name. Double click on the contents file name and your text editor should automatically open to display the names of files you have searched for along with the names of the rascals supplying the files. Double click on the file name and the name of the contents of the archive file will be displayed. Once the download has finished, use the "Open Folder" button on the download screen to open the folder where the zip file was saved. *NOTE: If you don't have a file archiver software installed, then download and install 7zip (freebie) from: Sending results to you as SearchBot_results_for_ jules. Search- > Your search for "jules verne" returned 424 matches. If the search is successful, then the channel will offer an achived text file (in zip format) which you can then accept for downloading. ![]() Search- > Your search for "jules verne" has been accepted. To search type the following (as an example) into the same entry bar previously Jules VerneĪfter a brief delay, you should see a prompt, similar to the following, that your search has been accepted. The "#ebooks" channel should then automatically open and you can then start searching for book titles, authors etc. Once it has finished logging onto that server, type the following into the entry bar at located at the bottom of the screen: Start Hexchat and then click on "Hexchat" drop down menu which is located at the top upper left.Ĭlick on "Network List" and then scroll down and highlight "Irchighway"Ĭlick on "Connect" located at the bottom lower right. There are FAQ and docs available there too. Use the following search term in each channel to see what is Jules Verne Network server ->us. -> log onto the #bookz channel Network server -> -> log onto the #ebooks channel Quote:Might want to try the following IRC channels using software such as Hexchat (freebie): Propbay's tl dr version (from the split post) ![]() You can also download install a easy to install package file getting the latest git version from the SourceForge. To push local changes and create merge requests.You can install Git on macOS Big Sur, Catalina, Mojave, Sierra, or an older Mac OSX version by a couple of options, one is to use Homebrew to install Git by installing Homebrew first and then issuing: brew install git You can now use the upstream as a to pull new updatesįrom the original repository, and use the origin It is common to call this remote repository the upstream. You must create a link to the remote repository to pullĬhanges from the original repository. To keep the project in sync with the original project, you need to pull from the original repository. To create a copy of a repository in your namespace, you fork it.Ĭhanges made to your copy of the repository are not automatically synchronized with the original. Synchronize changes in a forked repository with the upstream Advanced use of Git through the command lineįor an introduction of more advanced Git techniques, see Git rebase, force-push, and merge conflicts. To create a merge request from a fork to an upstream repository, see theįorking workflow. In GitLab, you typically use a merge request to merge your changes, instead of using the command line. Are collaborating on the project with others, and don’t want your work to get mixed up.Ī new branch is often called feature branch to differentiate from the.Want to add code to a project but you’re not sure if it works properly.You’re ready to add your changes to the main codebase, you can merge your branch into You can work in your branch without affecting other branches. You can learn more on how Git manages remote repositories in theĪ branch is a copy of the files in the repository at the time you create the branch. You can create additional named remotes and branches as necessary. is usually the name of yourĮxisting branch. Repository was cloned from, and it indicates the SSH or HTTPS URL of the repository When you clone a repository, REMOTE is typically origin. Git automatically creates a folder with the repository name and downloads the files there. Open a terminal and go to the directory where you want to clone the files.Go to your project’s landing page and select Clone.Authenticate with GitLab by following the instructions in the SSH documentation.Clone with SSHĬlone with SSH when you want to authenticate only one time. This connection requires you to add credentials. When you clone a repository, the files from the remote repository are downloaded to your computer, You can fork any project you have access to. In the upper-right corner, select Fork.To use the repository in the examples on this page: You can use any project you have permission toĪccess on or any other GitLab instance. Choose a repositoryīefore you begin, choose the repository you want to work in. You can read more on how Git manages configurations in the If you omit -global or use -local, the configuration applies only to the current The -global option tells Git to always use this information for anything you do on your system. You can determine if Git is already installed on your computer by opening a terminal On the Windows taskbar, select the search icon and type cmd. You can integrate it with Zsh and Oh My Zsh for color highlighting and other advanced features. Press ⌘ command + space and type terminal. ![]() Prompt, command shell, and command line). To execute Git commands on your computer, you must open a terminal (also known as command To help you visualize what you’re doing locally, you can install a Learn how GitLab became the backbone of the Worldline development environment.Watch the GitLab Source Code Management Walkthrough video.If you’re new to Git and want to learn by working in your own project,įor a quick reference of Git commands, download a Git Cheat Sheet.įor more information about the advantages of working with Git and GitLab: ![]() Like fixing complex merge conflicts or rolling back commits. However, the command line is required for advanced tasks, You can do many Git operations directly in GitLab. Git is an open-source distributed version control system.
![]() To make this more appealing, you can also run Linux apps from your Chromebook, which helps to convert it to a more traditional OS. You can also enable Linux support in Chrome OS and install and run Linux apps. No fuss, no muss, and a lot more useful than whatever you're currently running on an older PC. ![]() With this ChromeOS variant, you can convert pretty much any PC or Mac that's been built since 2007 into a much safer and more usable Chromebook clone. Neverware, formerly an independent company and now a branch of Google, offers ChromeOS Flex. You also don't need to buy a Chromebook to use Chrome OS. I mean, if you're reading this article via a web browser, which you almost certainly are, you already know how to use "Linux" enough to work with a Chromebook. While you can get to Linux from Chrome OS, you'd never need to look under the hood.Īnyone can use Chrome OS. The good news is that you don't need to know a darn thing about it. Chrome OS is the operating system that runs Chromebooks and is based on Gentoo, which is an experts-only Linux. To be clear, Chrome OS is not technically Linux but rather an OS based on Linux that uses the Linux kernel. MATE is also available on Mint.Ĭhrome OS features: Price: Free | Core code: Gentoo Linux | Open source? Yesĭo you use the web for everything? Do you write with Google Docs, use Mint for your personal finances, and Gmail for your email? If that's you, then what you want is a Chromebook. While Cinnamon rests on the foundation of the GNOME 3.x desktop, MATE is an outright GNOME 2.x fork WHAT DOES 2.X FORK MEAN? Explain that. Another worthwhile alternative for people who are fond of GNOME 2.x that is also integrated into Mint is MATE because of _. Linux users who grew up with the GNOME 2.x style interface will also love Cinnamon due to its _ and _. It's not a one-to-one match with XP or Windows 7, but most Windows users will find Cinnamon a comfortable fit. It uses a Windows Icon, Menu, and Pointer (WIMP) interface much like the one you probably already know and love. Mint with several desktop environments like Cinnamon looks a lot like XP or Windows 7. And my current favorite desktop operating system is Linux Mint 20.2. What's a Windows 10 user to do? They should turn to Linux Mint, in particular, the version using the Cinnamon interface. Linux Mint features: Price: Free | Core code: GNOME 2.x | Open source? Yes If you see inaccuracies in our content, please report the mistake via this form. If we have made an error or published misleading information, we will correct or clarify the article. Our editors thoroughly review and fact-check every article to ensure that our content meets the highest standards. Our goal is to deliver the most accurate information and the most knowledgeable advice possible in order to help you make smarter buying decisions on tech gear and a wide array of products and services. ZDNET's editorial team writes on behalf of you, our reader. Indeed, we follow strict guidelines that ensure our editorial content is never influenced by advertisers. Neither ZDNET nor the author are compensated for these independent reviews. This helps support our work, but does not affect what we cover or how, and it does not affect the price you pay. When you click through from our site to a retailer and buy a product or service, we may earn affiliate commissions. And we pore over customer reviews to find out what matters to real people who already own and use the products and services we’re assessing. We gather data from the best available sources, including vendor and retailer listings as well as other relevant and independent reviews sites. ZDNET's recommendations are based on many hours of testing, research, and comparison shopping. ![]() ![]() ![]() G_grav = 9.80665* m/s/s # standard gravity The code would run much faster without the Unum units in every computation. I added the explicit units to check to see if we had any conversion errors (there were none). The code written by the students did not include explicit units, but did everything in standard SI units. Here is the latest draft of the simulation code, which uses the VPython library for graphing and the Unum library for handling units. I’d like help from the physics (or rocketry) experts, both on the simulation the students wrote (with help from me) and on how to do the empirical measurements to test the fit of the simulation. If the simulation predicts super-sonic air flow, then we need to change the model, since the lack of any expansion nozzle means that there is definitely a limitation to Mach 1 for the air jet. For example, we have not simulated any friction for the water or air leaving the bottle, nor checked to see whether the air flow is subsonic (I think it is). Look for phenomena we haven’t properly included in the simulation.For height, we are probably limited to a trigonometric measurement, but I have my doubts about the accuracy of measurement with a protractor and plumb-bob. Lots of people do water and compressed-air rocket labs of various sorts-what do they measure and how? I considered measuring time of flight (which is simpler to measure than height), but the variation in time of flight is fairly small. My main concern here is coming up with an accurate measurement. Do a lot of launches with various amounts of water and measure the flights.One thing that the model does get right is that it predicts a much higher flight for a 14g paper and masking tape “rocket” fired with compressed air off a 30cm long launching tube than for a 42g bottle off the triggered launcher. ![]() We consistently get that the amount of water for max height is around 1/9th the volume of the bottle, but I seem to remember getting the best results in the past with amounts around 1/3rd. We now have a simulation that has roughly the right values at the extremes (empty bottle and full bottle), and that peaks at an intermediate value, but I’m still not convinced that the model works properly. We didn’t measure barometric pressure, temperature, and humidity ourselves, but relied on reports on the web from a local weather station a couple blocks away. The model with both the water jet and the air jet predicted too high a max height, so one more term was added: a drag force proportional to the velocity squared.Īll the parameters except the drag coefficient (and frontal area, if the bottle tumbles) are directly measured, except for the local gravitational field for which we used a Wolfram Alpha widget. By this point I was heavily involved in the modeling, because I wanted a model that we could use. The model was then improved by adding an air jet after the water was expelled, using essentially the same equations as for the water jet, but with lower density and a slightly different update for the pressure on each time step. The first simulation, which was done almost entirely by the students, predicted much too low a max height, because it only included two sources for thrust: the initial slide off the launcher (using a simple energy model and constant pressure), and conservation of momentum as the water was expelled. Then they did some preliminary tests to see whether the simulation was anywhere near correct (with 0g of water and with 400g of water). The bottle here has no pressure in it, so did not leave the launcher, even though the lever is pulled back to release position.įirst, I insisted on them coming up with equations to model the rocket and writing a simulation, so that they could optimize the amount of water to put in the rocket. Note that we had to add a paperclip to the launch lever as a jump ring, since the hook provided for the cord would not reach the hole in the lever intended for it. The stake can be seen just to the right of the bottle. |
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