Physics Formula Help : How To Apply A Physics Formula

As we grow older, we are faced by a greater and greater number of physics formulas. Are you tempted to use a formula at the slightest relation that you may see? Look before you leap, its a wise thing to carefully think before you apply any formula to a problem.

The first step in this regard is to 'correctly' identify the formula :

1. Scan the question to see what physical quantity is to be calculated. Is it some length? Or some force?

2. Identify the specifics of the unknown. For example, is it the length between A & B? Is it the force by P?

3. Now think of a formula that relates this quantity with the quantities known in the question. It could be that the quantity you are required to calculate is not given by any single formula directly. In that case, you may have to apply more than one formula to reach the result.

4. This one's a crucial step. Try to recall the precise condition for which the formula has been designed. Here are a few things that might be specified:

• Be careful about the symbols used in an equation. Sometimes a symbol used in the equation may refer to a physical quantity that is different from what the symbol usually represents.
• Often, the lowercase and uppercase of the same letter or symbol may represent different physical quantities. Be sure to correctly recollect the name, representation and the case of the symbols used in the equation.
• Values of the constants used in the equation may be universal or may be specified for some particular conditions. The values of most universal constants are given in the question or paper itself.
• A formula is generally meant for a particular condition imposed on some of the variables that may or may not be present in the equation. In fact, the question may state certain values or conditions only to justify the formula to be used.
• Some assumptions may have been taken during the derivation of the formula which, if violated in the condition described in the question, makes the formula inapplicable.

Now moving on to the second task - correctly substituting the information given in the question into the formula.

1. Read the values correctly. Double check the numbers when you copy them. It's a bit discouraging when you take the trouble of solving the entire equation and discover in the end that you substituted wrongly in the first place!
2. Use the proper relations to obtain the value of the quantity mentioned in the equation from the value of the quantity given in the question.
   
3. Don't forget your unit conversions! Bring all your quantities to a common system of units like the SI system or f-p-s system. This way you automatically know the units of your answer.

Having done the above, you only need to calculate the answer. The formula application part is over. I can't emphasize enough the need of being careful at every step. There are innumerable ways to make mistakes while using formulas and carefulness is the biggest weapon you have.

Finally, here are some tips to help remember formulas:

1. Formula Sheets : It is important to list down all your formulas in one place. You can use a website that lists the formulas or even better, write them down yourself.
2. Form a 'clear picture' in your mind of the condition under which the formula is to be applied.
3. Write and practice the formulas. Pay attention to the case of the symbols. Along with the formula, always write down all the assumptions and the key to all the symbols used.
4. Whenever you read a formula, try to connect each of the symbols with the quantities they represent.

So there you go! It's that simple and time you cracked all the problems in your physics class.