Science Articles

Cheat Sheet / Updated 11-08-2022

Chemistry covers all kinds of stuff. Sometimes you might not be sure where to start when you are first given a set of problems and told to go forth and succeed. Sometimes it’s converting metric units, writing ionic formulas, naming covalent compounds, balancing reactions, or dealing with extensive and intensive properties. This Cheat Sheet is designed to give you some help on a few of the trickier things you might encounter so that when you are done looking it over you can go forth and succeed!

Article / Updated 10-26-2022

A conversion factor uses your knowledge of the relationships between units to convert from one unit to another. For example, if you know that there are 2.54 centimeters in every inch (or 2.2 pounds in every kilogram or 101.3 kilopascals in every atmosphere), then converting between those units becomes simple algebra. It is important to know some common conversions of temperature, size, and pressure as well as metric prefixes. Conversion factor table The following table includes some useful conversion factors. Using conversion factors example The following example shows how to use a basic conversion factor to fix non-SI units. Dr. Geekmajor absentmindedly measures the mass of a sample to be 0.75 lb and records his measurement in his lab notebook. His astute lab assistant, who wants to save the doctor some embarrassment, knows that there are 2.2 lbs in every kilogram. The assistant quickly converts the doctor’s measurement to SI units. What does she get? The answer is 0.34 kg. Let’s try another example. A chemistry student, daydreaming during lab, suddenly looks down to find that he’s measured the volume of his sample to be 1.5 cubic inches. What does he get when he converts this quantity to cubic centimeters? The answer is 25 cm3. Rookie chemists often mistakenly assume that if there are 2.54 centimeters in every inch, then there are 2.54 cubic centimeters in every cubic inch. No! Although this assumption seems logical at first glance, it leads to catastrophically wrong answers. Remember that cubic units are units of volume and that the formula for volume is Imagine 1 cubic inch as a cube with 1-inch sides. The cube’s volume is Now consider the dimensions of the cube in centimeters: Calculate the volume using these measurements, and you get This volume is much greater than 2.54 cm3! To convert units of area or volume using length measurements, square or cube everything in your conversion factor, not just the units, and everything works out just fine.

Article / Updated 10-19-2022

Celebrate everything that is beautiful about our planet by reconnecting with nature, learning more about the natural environment, or picking up a new eco-friendly habit or two. April 22 is Earth Day — a world-wide celebration commemorating everything that makes our blue-marble planet unique and beautiful, and all the things we can do to protect it. Starting all the way back during the environmental movement of the 1970s, Earth Day has grown to become a powerful motivator for individuals and companies alike to become more environmentally aware and responsible. From local volunteer cleanups to nation-wide conservation initiatives, this year is no different, with numerous events happening at both the grassroots and state levels. Want to join in on the celebration? Find Earth Day events in your area, by visiting https://www.earthday.org/ The First Earth Day Did you know... In response to public outcry to the Santa Barbara Oil Spill of 1969, U.S. Sen. Gaylord Nelson organized a nationwide "teach-in" about environmental issues to take place on April 22, 1970. More than 2,000 colleges and universities, 10,000 public schools, and 20 million citizens participated. Aside from volunteering or donating to an eco-friendly cause, there are plenty of other ways to celebrate Earth Day — here are just a few. Plant a healthy diet You’ve probably already heard about the massive environmental impact that animal farming has on the planet. It is second only to fossil fuels in terms of contributing to human-made greenhouse gas emissions, the cause of climate change. And, while the jump from a traditional omnivorous diet to a full-blown vegan one is not something most people can accomplish overnight, cutting down on red meat is a great first step. Something as simple as committing to meat-free Mondays can have a significant influence on your health and the environment. Get started by taking a crack at one or two of our favorite plant-based recipes found in Plant-Based Diet Cookbook For Dummies. Channel your inner green thumb You don’t need to become an expert horticulturist to help save our planet. Simply buying local or better yet, growing some of your own food can help reduce your carbon footprint — not to mention, teach you valuable transferable skills like diligence and patience. Plus, there’s just something so satisfying about working with your hands, especially if you’re used to working in front of a screen all day. You can start by growing some common herbs like rosemary or thyme. They are fairly resilient and, depending on where you live, can even be grown indoors. If you lack the space to garden, look for farmers markets in your area or, better yet, join a community garden, these gardens are becoming increasingly popular, even in the most urban of cities. Don't worry if you have no previous gardening knowledge — beginner-friendly resources, such as Gardening Basics For Dummies, will help you get there. You can also find a farmers market near you using the USDA National Farmers Market Directory. Stay informed It’s no secret that our planet is in grave danger as a result of climate change. But, contrary to what you may feel after reading all the increasingly worrisome headlines, you must remember — there’s still hope. And, while the biggest contributors of climate change, like animal farming and fossil fuel burning, may seem so far removed from your daily life, you’d be surprised how much of a difference you as an individual can make. Staying informed is perhaps the easiest way to help environmental causes. As an informed citizen, you have the power to choose more wisely what products to buy, what companies and practices to support, and even who you vote for in the next election. Don't know where to start? Check out Climate Change For Dummies to help you navigate this complex topic. More ways to greenify your life There’s always something more we can do to reduce our environmental impact on the planet, but that should not discourage us from taking action — after all, every little bit counts. One small change in your daily routine today will lead you to more and more lasting changes in the future. If you’re ready to explore even more ways to go green, check out Green Living For Dummies for a more comprehensive guide to sustainable living. From the team at Dummies, we wish all our fellow earthlings a happy and green Earth Day.

Article / Updated 10-07-2022

Knowing the four lobes of the brain is important for neuroscience. The neocortex is divided into four major lobes: the frontal lobe, the parietal lobe, the temporal lobe, and occipital lobe. These lobes are further divided into different regions. The frontal lobes are involved with control of movement, from stimulation of individual muscles to abstract planning about what to do. The parietal lobe processes visual, auditory and touch information. The temporal lobe is the primary area for early auditory processing and a high-level visual processing area. It also processes some aspects of smell (olfaction). The occipital lobe processes visual information and sends it to the parietal and temporal lobes. Taste and some olfaction are processed in the posterior frontal lobe. The four lobes and the regions within each. The frontal lobe The frontal lobe is concerned with executing behavior. This ranges from the control of individual muscles in the primary motor cortex to high level abstract planning about what to do. The frontal lobes are divided into different areas: The prefrontal cortex: In humans, the prefrontal cortex takes up the majority of the frontal lobe. The prefrontal cortex is crucial for the performance of almost all skills requiring intelligence. The prefrontal cortex tends to be larger in primates than other mammals, and it’s larger in humans than in other primates. This is correlated with the amount of high level planning done by members of different species. Most mammals operate mostly on instinct and don’t live in complexly differentiated social groups. Primates, on the other hand, have complex male and female hierarchies and may hatch plots against each other that span years of planning. Humans build tools, modify their environments for their own purposes, and have specific relationships with up to hundreds of other individuals (and this was even before Facebook). The orbitofrontal cortex: This area is the anterior and medial part of the prefrontal cortex. The orbitofrontal cortex is essential for risk and reward assessment and for what might be called moral judgment. Patients with damage to this area may have normal or superior intelligence as assessed by IQ tests but lack even a rudimentary concept of manners or appropriate actions in social contexts; they also lose almost all risk aversion despite clear knowledge of bad consequences. Primary motor cortex: The primary motor cortex is the strip of brain area just anterior to the central sulcus, the most posterior portion of the frontal lobe. The brain can take direct control of the muscles from the spinal cord. It does this through projections from the primary motor cortex. Neurons in the primary motor cortex travel down the spinal cord and synapse on the same motor neurons that mediate reflexes. In theory, this direct control allows far more flexibility and adaptability. Premotor cortex: The job of the premotor cortex is to consciously monitor movement sequences, using sensory feedback. After the basal ganglia and prefrontal cortex select the goal, the premotor cortex coordinates the steps to reach that goal. Activity in the premotor cortex helps you learn what to pay attention to while you perform a complicated motor sequence and what to do when you get stuck at some particular point. Think of the frontal cortex as “polarized” from anterior (front) to posterior (back). Farthest back, at the central sulcus, are neural wires going almost directly to muscles. In front of that are areas that organize and sequence movements. In front of that are abstract planning levels. At these abstract levels, for example, you select from a variety of different strategies that may involve completely different muscles, muscles sequences, or, as in the tennis shot, the decision to not move at all. The parietal lobe The parietal lobe contains neurons that receive sensory information from the skin and tongue, and processes sensory information from the ears and eyes that are received in other lobes. The major sensory inputs from the skin (touch, temperature, and pain receptors) relay through the thalamus to parietal lobe. The occipital lobe The occipital lobe processes visual input that is sent to the brain from the retinas. The retinas project through the thalamus onto the posterior pole of the occipital lobe, called V1 (for visual area one), so that activity in different areas of V1 is related to whatever is in the image around your current point of gaze. Subareas beyond V1 specialize in visual tasks such as color detection, depth perception, and motion detection. The sense of vision is further processed by projections from these higher occipital lobe areas to other areas in the parietal and temporal lobes, but this processing is dependent on early processing by the occipital lobe. (Researchers know this because damage to V1 causes blindness in that part of the visual field that projects there.) The fact that the visual system gets an entire lobe for processing emphasizes the importance of high visual acuity and processing among our senses. The temporal lobe The brain’s temporal lobe combines auditory and visual information. The superior (upper) and medial (central) aspect of the temporal lobe receives auditory input from the part of the thalamus that relays information from the ears. The inferior (lower) part of the temporal lobe does visual processing for object and pattern recognition. The medial and anterior parts of the temporal lobe are involved in very high-order visual recognition (being able to recognize faces, for example), as well as recognition depending on memory.

Article / Updated 10-06-2022

Thanks to the principle of conservation of mechanical energy, you can use physics to determine the final height of a moving object. At this very moment, for example, suppose Tarzan is swinging on a vine over a crocodile-infested river at a speed of 13.0 meters/second. He needs to reach the opposite river bank 9.0 meters above his present position in order to be safe. Can he swing it? The principle of conservation of mechanical energy gives you the answer: At Tarzan’s maximum height at the end of the swing, his speed, v2, will be 0 meters/second, and assuming h1 = 0 meters — meaning that he started swinging from the same height as the tree branch he's swinging to — you can relate h2 to v1 like this: Solving for h2, this means that Tarzan will come up 0.4 meters short of the 9.0 meters he needs to be safe, so he needs some help.

Article / Updated 10-06-2022

At some point, your quantum physics instructor may want you to find the x, y, and z equations for three-dimensional free particle problems. Take a look at the x equation for the free particle, You can write its general solution as where Ay and Az are constants. Because you get this for where A= Ax Ay Az. The part in the parentheses in the exponent is the dot product of the vectors That is, if the vector a = (ax, ay, az) in terms of components and the vector b = (bx, by, bz), then the dot product of a and b is So here’s how you can rewrite the

Article / Updated 10-06-2022

At some point, your quantum physics instructor may want you to add time dependence and get a physical equation for a three-dimensional free particle problem. You can add time dependence to the solution for if you remember that, for a free particle, That equation gives you this form for Because the equation turns into In fact, now that the right side of the equation is in terms of the radius vector r, you can make the left side match: That’s the solution to the Schrödinger equation, but it’s unphysical. Why? Trying to normalize this equation in three dimensions, for example, gives you the following, where A is a constant: (Remember that the asterisk symbol [*] means the complex conjugate. A complex conjugate flips the sign connecting the real and imaginary parts of a complex number. The limits on the integral just mean to integrate over all of space, like this: Thus, the integral diverges and you can’t normalize as written here. So what do you do here to get a physical particle? The key to solving this problem is realizing that if you have a number of solutions to the Schrödinger equation, then any linear combination of those solutions is also a solution. In other words, you add various wave functions together so that you get a wave packet, which is a collection of wave functions of the form such that The wave functions interfere constructively at one location. They interfere destructively (go to zero) at all other locations. Look at the time-independent version: However, for a free particle, the energy states are not separated into distinct bands; the possible energies are continuous, so people write this summation as an integral: So what is It’s the three-dimensional analog of That is, it’s the amplitude of each component wave function. You can find from the Fourier transform of like this: In practice, you choose yourself. Look at an example, using the following form for which is for a Gaussian wave packet (Note: The exponential part is what makes this a Gaussian wave form): where a and A are constants. You can begin by normalizing to determine what A is. Here’s how that works: Okay. Performing the integral gives you which means that the wave function is You can evaluate this equation to give you the following, which is what the time-independent wave function for a Gaussian wave packet looks like in 3D:

Step by Step / Updated 10-06-2022

Living on Earth can be dangerous. Earth is a dynamic planet, geologic processes are always in motion, and while some processes take millions of years (like the formation of a sedimentary rock), others happen very quickly (like a volcanic eruption). All these processes are natural, but they become hazards when they affect human lives and the infrastructure of modern society.

Article / Updated 10-03-2022

A hurricane starts as a tropical storm, and a tropical storm reaches hurricane status when it develops and sustains winds moving at least 74 miles per hour. The storm itself is a cyclone with winds spiraling (at least in the Northern Hemisphere) in a counterclockwise direction. These cyclones, or rotating storms, develop over any ocean but are called hurricanes when they arise over the Atlantic or Northern Pacific. In other areas, they’re called typhoons or tropical cyclones. How does a hurricane form, and when is hurricane season? How a hurricane comes together isn’t precisely known, but it requires warm water (at least 79 degrees Fahrenheit) and winds that rise without much change in direction. Those factors combine to create winds that move in a spiral. As a storm grows, it may cover a diameter of more than 600 miles and gust at more than 200 miles per hour — nearly the top speed of a Formula One racecar. The faster the wind, the higher the storm rating and the greater the threat to everyone and everything in its path. Hurricanes are rated by intensity on a scale of 1 to 5, with a Category 1 storm showing the lowest intensity and winds of no more than 95 mph. Those in Category 5 top 156 mph. Hurricanes Maria (Dominica and Puerto Rico) and Irma (Florida) were Category 5 storms that made landfall in 2017. Windows and doors may get smashed from winds at the Category 2 level and above. Hurricane season runs from late May through November. What is the center of a hurricane, and other storm anatomy questions A hurricane is made up of several parts. If you could look closely at a cross-section of a hurricane, here’s what you’d see, starting from the center of the hurricane: Eye: An oasis of calm surrounded by hurtling winds and rain, the eye of a hurricane is about 20 to 40 miles of low winds, light rain, and even clear skies where the air is sinking rather than rising. Eye wall: Swirling around the eye, the eye wall is a band of thunderstorms where the rain and wind are strongest. Air is moving rapidly here in the direction of the eye of the storm, rising before it sinks again at the storm’s center. Feeder bands: Stretching sometimes hundreds of miles from the center of the storm, feeder bands of a hurricane are bands of heavy rain and wind sometimes include tornadoes. Outflow: Hurricanes stretch up much farther than out. Way up at a plane’s cruising altitude, the outflow of a hurricane is a huge swath of clouds swirling in the opposite direction of a hurricane. Hurricane prone areas If you live in Montana, you’re in the clear. Because hurricanes develop over warm ocean waters and lose strength as they travel over land, they do their worst near the country’s coasts. Here are the counties and areas that are prone and have been most often hit from 1960 to 2008, according to the U.S. Department of Commerce: Monroe County, Florida Lafourche Parish, Louisiana Carteret County, North Carolina Dare County, North Carolina Hyde County, North Carolina Jefferson Parish, Louisiana Palm Beach County, Florida Miami-Dade County, Florida Bernard Parish, Louisiana Cameron Parish, Louisiana What is hurricane storm surge? Hurricanes form over warm oceans, and when they reach land they push huge amounts of ocean water onto the shore with them. This is usually described as a “wall of water” but more specifically is an extremely fast rise in water above sea level. It technically is known as the storm surge. During Hurricane Katrina in 2005, the storm surge topped 25 feet and was a major factor in that storm’s high death toll. (At least 1,500 people died during Katrina.) A storm surge unleashes the incredible power of wind and water, sweeping up trees, cars, and buildings as it moves. Even standing in just six inches of these powerful waters would be difficult. A storm surge may reach land ahead of the storm, and when it does it may flood the roads you’d have used to evacuate. If you live near the shore, get out well in advance of the storm’s landfall. The storm surge may hit a day earlier, and it’s the deadliest element of a hurricane. The elements of a storm surge, like strength and angle of the storm, the shape of the land where it hits, and the shape of the continental shelf at the coastline, combine in unpredictable ways. In other words, no one can predict the intensity of a storm surge. Erring on the side of caution is warranted, especially when you consider that a cubic yard of water weighs almost a ton. The risk of damage from a storm surge is highest in the following states: Florida Louisiana Texas New Jersey New York You don’t have to live on a coast to get hit by the rains and winds a hurricane creates, and if you are in a high-risk area, you need to take steps — before hurricane season hits — to prepare yourself, your family, and your home for the potentially deadly damage. A hurricane is nature at its most destructive. These tropical cyclones don’t sneak up: When a hurricane is on its way, you’ll have several days’ warning before it lands, so keep an eye on the news or sign up for hurricane alerts. But sometimes several days isn’t enough. If you act much earlier, you won’t be fighting your neighbors for the last jugs of water on the store shelves. Create a hurricane preparedness checklist You want to prepare for a hurricane before hurricane season even starts, and a hurricane preparedness checklist can help you make sure you’ve got everything in order. Avoid the mad dash for supplies by prepping a hurricane disaster supply kit before you’re likely to need it. You want a large plastic tub or duffle bag so that everything in your kit is in one place and is ready to move. Pack it with the following: Water jugs: Traditional wisdom says bring a gallon per person per day for a minimum of three days. If you have room to carry it, err on the side of too much water. Food: Pack up enough nonperishable food for a few days — and a can opener. Think canned tuna and fruit, dry cereal, peanut butter, or granola bars, and focus on high-energy foods rather than salty snacks that will lead you to use too much of your water. Pack foods you like and some comfort foods because you’re going into a high-stress situation. No need to add to your angst. First-aid kit Flashlight and extra batteries Portable radio (you may not have Internet service) and extra batteries Cellphone charger Toilet paper Blankets or sleeping bags Glasses or contacts and contact solution A change of clothes for each family member Distractions like games, toys, and books Pet food Insect repellent Whistle (to signal for help) or flares Waterproof containers or plastic bags Other ways to prepare for a hurricane Preparation isn’t just what you do when a storm is imminent. Many of the moves that best protect you are the ones you make far ahead of time, like building a hurricane kit. You also want to take these steps: Have a plan. And make sure everyone in your household knows it. Choose a point person for everyone to contact and a meeting place if you get separated. Stay current on weather conditions. Keep a close eye on weather updates and emergency guidelines for your area. Minimize tree-related damage. Remove any dead wood from your trees; keep them trimmed so that they’re healthy and branches don’t reach your home. Maintain your car. Keep your car in good working order; gas up your tank when a storm nears. Protect your windows. Plan how you’ll protect your windows with permanent storm shutters or plywood. Long before a storm hits, make sure you have the right number and sizes of 5/8-inch-thick plywood sheets ready to be nailed in. Reinforce your exterior doors. They’re more likely to stay put against a hurricane if they’re secured by three hinges per door and a one-inch deadbolt. Prepare for rain run-off. Regularly clean gutters and drains so that they’re in the best shape to handle heavy rain. Get and maintain the right insurance. Purchase adequate homeowner’s insurance and become well-acquainted with its terms. Arm yourself with information Several organizations specialize in weather and emergency information. Check out these resources for further details about staying safe in a hurricane: The American Red Cross offers several guides for hurricane preparedness and safety and can tell you how to donate to relief efforts. FEMA keeps you alerted to storm progress, evacuation orders, and shelter locations during a hurricane. The Department of Homeland Security’s gov gives you hour-by-hour checklists of preparation and safety guidelines for hurricanes. You can track a storm through the National Hurricane Center Weather Underground tracks tropical storm and hurricane activity in tremendous detail and offers historical data as well as general preparedness information. For official communications related to hurricanes, please visit the websites of FEMA, Department of Homeland Security, and the National Hurricane Center for the latest information. Please note that this is general preparedness information, not specific to a particular storm.

Article / Updated 09-27-2022

Many people find Physics to be a difficult subject to approach. Well now, you have some tools to help you along the way. This handy list of physics equations organized by topic contains the most common equations you’ll run across: