0IDENTIFY the relevant concepts: Use the physical conditions stated in the problem to help you decide which physics concepts are relevant. Identify the target variables of the problem—that is, the quantities whose values you’re trying to find, such as the speed at which a projectile hits the ground, the intensity of a sound made by a siren, or the size of an image made by a lens. Identify the known quantities, as stated or implied in the problem. This step is essential whether the problem asks for an algebraic expression or a numerical answer.
SET UP the problem: Given the concepts, you have identified and the known and target quantities, choose the equations that you’ll use to solve the problem and decide how you’ll use them. Make sure that the variables you have identified correlate exactly with those in the equations. If appropriate, draw a sketch of the situation described in the problem. (Graph paper, ruler, protractor, and compass will help you make clear, useful sketches.) As best you can, estimate what your results will be and, as appropriate, predict what the physical behaviour of a system will be. Practice!!
EXECUTE the solution: This is where you “do the math.” Study the worked examples to see what’s involved in this step.
EVALUATE your answer: Compare your answer with your estimates, and reconsider things if there’s a discrepancy. If your answer includes an algebraic expression, assure yourself that it represents what would happen if the variables in it were taken to extremes. For future reference, make note of any answer that represents a quantity of particular significance. Ask yourself how you might answer a more general or more difficult version of the problem you have just solved.
