Summarize the following:
In order to understand capillary action, you first need to understand adhesion and cohesive forces. Adhesion is the force that causes a liquid to stick to a solid surface, such as the edge of a glass. Cohesive forces are those that pull liquid molecules toward each other. The combination of adhesion and cohesive forces causes a liquid to rise up the center of a thin tube.  The height the liquid rises can be used to calculate the surface tension of that liquid. Cohesion causes water to form bubbles or droplets on a surface. When a liquid is in contact with air, the molecules feel attractive forces towards each other and make a bubble on the surface. Adhesion causes the meniscus that is seen in liquids when they cling to the sides of a glass. It is the concave shape at the top of the liquid seen at eye level.  An example of capillary action is watching water rise in a straw placed in a cup of water. Surface tension is given by the equation S = (ρhga/2) where S is the surface tension, ρ (or rho) is the density of the liquid you are measuring, h is the height the liquid rises in the tube, g is the acceleration due to gravity acting on the liquid (9.8 m/s2) and a is the radius of the capillary tube.  When working through this equation, make sure all of your units are in the proper metric form: density in kg/m3, height and radius in meters, and gravity in m/s2. If the density of the liquid is not given, you can look it up in a reference book or calculate it using the equation density = mass/volume. The unit for surface tension is one newton per meter (N/m). A Newton is equal to 1 kg-m/s2. To work out the units on your own, simply solve the equation with just units. S = kg/m3 * m * m/s2 * m. Two of the meter units cancel out two of the per meter units and you are left with 1 kg-m/s2/m or 1 N/m. Using a shallow dish or bowl, fill it with about an inch of the liquid in question. The amount of liquid added does not matter as long as you can clearly see the rise in liquid within the capillary tube. If you repeat this with different liquids, make sure the dish is thoroughly cleaned and dried before adding the next liquid. Alternatively, just use separate dishes for each liquid. This is the tube that you will take your measurements from to calculate the surface tension. The tube must be clear so that you can see how far the liquid rises above the level in the dish. The tube must also have the same radius throughout.  To measure the radius, simply place a ruler across the top of the tube and determine the diameter. Divide the diameter by 2 and you have the radius. You can buy these tubes online or from a hardware store. Place the bottom of a ruler directly above the liquid in the dish and measure how high the liquid has risen into the tube. The water rises due to the upward force of surface tension being greater than the downward force of gravity. Once you have determined all of the necessary variables, you can plug them into the formula and solve for surface tension. Remember to convert all of your values to metric so the problem can be solved properly.  For example, let’s say we are measuring the surface tension of water. Water has a density around 1 kg/m3 (we will use approximate values in this example). The variable g is always 9.8 m/s2. The radius of the tube is .029 m and the water rises 0.5 m. What is the surface tension of the water? Plugging the variables into the equation yields: S = (ρhga/2) = (1 x 9.8 x 0.029 x 0.5)/2 = 0.1421/2 = 0.071 J/m2.

summary: Understand capillary action. Define the equation to solve for surface tension. Fill a container with the liquid of unknown surface tension. Place a clear, thin tube into the liquid. Measure the height the liquid rises above the liquid in the container. Plug the measured values into the equation and solve.


Summarize the following:
One way to find "expensive" items is to pay attention to brand names. High-end brands will generally turn a higher profit. However, unique items can also turn a decent profit, if it's something that's weird enough that a person will pay more for it. One way to determine if an item is worth buying and flipping is to check its price online. Try searching for the item on a site like eBay, for instance, which can tell you how many items are out there and what an item like that is selling for. Use the brand name, the item name, and the color to search, if possible. Once you get going, you can flip any kind of item you want. Nonetheless, when you're in the beginning stages, try sticking to one category. That way, you can get to know the product you're looking for, and you'll soon know what's valuable and what's not. When you're discovering your niche, research the items online. See what they generally sell for. Also, look to see what makes one of those items "special" or "unique." For instance, if you're reselling books, often a vintage or first edition book will command a higher price than other items. Similarly, certain brands of vintage clothes will command high prices, and some even more so if they are rare or unique. Doing some research first is essential to knowing what to buy. While you may want to eventually get into higher priced items, when you're first starting out, it's best to pick items that cost less. That way, you're not risking too much money. Try to keep the items you buy under $20 apiece. It can be tempting to spend a little more for an item you become attached to. However, you always need to keep your profit in mind. If you don't think you can buy it at a certain price and make a profit, just walk away from it. You'll find something else later.  It's important to think about how the price of the item will affect your end profit. That's why research is so important. Once you know what an item will generally sell for, it's easier to decide how much you should pay for an item. Sit down and figure out how much it costs you to ship and list an item. Also, factor in gas mileage, as well as paying yourself for the time it took to go find the item. Now, compare that to what you are asked to pay for the item. If it doesn't cover at least those costs, it's not worth it.
summary: Look for expensive and/or unique items. Search for the product online. Start with a niche. Begin with smaller items. Don't overspend.