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Some words used in physics are commonly used in everyday speech, like “energy” or “momentum”. When used in physics, though, remember that these words have precise mathematical definitions. Learning this stuff is difficult. The challenge is fun, but don’t be surprised if you have to struggle with a difficult problem. This is normal, and does not indicate that you are bad at Physics. It is common to come across a concept you thought you understood, and to find that you did not. People in general have a hard time letting go of erroneous ideas, so such misconceptions can be a huge roadblock to constructing a correct mental model. Be prepared to abandon ideas that you might have cherished or which seem natural or correct. Memorize frequently-used equations and constants. Knowing the relevant equation doesn't mean you understand the concept, but it's hard to understand the concept without knowing the equation. When doing the reading, do the examples and practice problems yourself.
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Problem-solving strategies: Not all of these are applicable in every situation, but nevertheless, keeping these tips in mind will help you tremendously. When starting a word problem, write down all the given information (values of variables), including information that is only implied in the problem. Draw a diagram. In problems involving forces, identify and draw all forces acting on the object in question. Figure out which equations are relevant to the situation. Write them down, even if you’re not sure you will need them. You are looking for an equation that relates the information you know, and the information you are trying to calculate. Put a box around every variable whose value you know. If you have n equations with n unknowns, you have enough to complete the problem. Include short text explanations of your reasoning. Solve problems algebraically, BEFORE plugging in numbers. This allows you to see the relationships between variables that are hidden when specific numbers are used. After doing much algebra to reach a solution to a problem, check that the units are correct. Units follow the same rules of algebra as variables and numbers do. Plug in the numbers and calculate the answer. Always write the units associated with any number. When you calculate a final numerical answer, STOP and ask yourself if it makes sense. Very often a trivial algebra or calculation error results in a ridiculous answer that you will see is obviously wrong, if only you stop and do a “sanity check”.
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