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Quick tips to recollect formulae during examination

Formulae during examinationThe secret to crack any competitive examination lies in efficient time management. Here every second counts and so any student serious to crack exam cannot afford to giving formulae a miss. However, this task is easier said than done.  With clock ticking on one hand and huge number of un-attempted questions on the other, students often find it difficult to recollect formulae during examination. However, there are certain simple rules which when followed enable us to remember formulae correctly and remove any doubt that may arise due to pressure of examination.

Notice catch words

Notice catch wordsMaking note and recognition of catchwords is first step towards correct formula recollection.  These catchwords are intended in question to make data recognition difficult for students, which eventually increases the time required. For example, In physics, instead of mentioning initial velocity as zero, question is presented as a body was at rest, which also implies u = 0 but is difficult to recognize as a data point. Therefore a careful reading of catchwords is necessary.

Taking another example from mathematics, instead of directly asking perimeter of base cylinder, length cloth required to wrap the cylinder may be asked.  In haste one may confuse it with length of cylinder. Unfortunately, sometimes wrong value is also option and eventually simple question becomes wrong. Therefore, first rule is to read question carefully and make notice of catchwords and encircle or underline them. The highlighting part also helps in tinkering brain to start working on appropriate formula in background and saves precious time.

Read question with formula labels

formula labelsWhile reading question, one should start labeling question with appropriate labels. For example, In a physics question, wherever one finds mention of final speed, a label of ‘v’ should be put and wherever acceleration is mentioned ‘a’ can be put and so forth. This would enable student to properly mark what parameter is asked and what all parameters are given. For example:

Question: A car accelerates down a road at 3.0 m/s2 for 2.8 s from rest. Determine the distance traveled by the car during this time?

While reading: one needs to label the question as: A car accelerates down a road at 3.0 m/s2 (a) for 2.8 s (t) from rest (u=0). Determine the distance traveled by the car during this time? (s=?). Hence, we can remember a formula with such terms as:  s = ut + ½ at2

Physical application

Physical applicationWhen we come across a formula, we tend to take it for granted. However, successful recollection of correct formula during examination requires that each formula is recollected in terms of physical relation.  Example: The basic law of motion says v2 - u2 = 2as, where‘s’ is displacement, ‘a’ is acceleration & ‘v’ is final velocity and ‘u’ is initial velocity. Here instead of trying to recollecting it as set of alphabets one needs to understand them and recall them as physical quantities, beginning by rewriting formula as: v2 = u2 +2as.

Now, one can think of a car whose initial speed is U and if the driver in pressing the accelerator for some distance then its speed will increase and would increase by factor of a*s, i.e. acceleration and for the distance driver has pressed accelerator on. Hence, final speed would be more and so addition sign would come.

Therefore, formula becomes, v2 = u2 +2as.  Thus if during examination if any doubt arises with regard to signs +/- or which parameter was on which side one should remember the physical relations and put them appropriately.

Checking Degrees

Checking DegreesNow again when we look at formula we see it as v2 = u2 +2as and not v = u + 2as. This doubt can be solved by remember one basic rule of degrees. i.e. degrees of all terms adding or subtracting in a formula has to be equal. v2  is actually v*v and so has degree of 2, similarly, u2 has degree of 2, therefore,  third term i.e. ‘a’ & ‘s’ would not get divided (a/s) or added( a+s) but would be multiplied (a*s).

Units Analysis

Units AnalysisFor question in Physics and Geometry, last minute check of units has to be done. For example: If question is to calculate acceleration of a particular vehicle whose initial and final speed is given and time taken to reach is also given.

One remembers, that a formula containing ‘a’ , ‘u’, ‘v’, ‘t’ would be used but does not remember if a = (v-u)*t or a= ( v-u)/t  one should check the units. Now ’a’ is always in m/s2 which is on right whereas ‘u’ & ‘v’ are given in m/s therefore one more time needs to come in denominator so that units of left hand side equals right hand side. Hence correct formula would be one where time is in denominator and hence a= (v-u)/t is correct formula.

Formula Sheet with question

Formula Sheet Almost everyone preparing for any competitive examinations prepares or gathers a formula notes where each formula used in concerned chapter is listed and one plans to read these truck load formula’s on morning just before examination. However, during course of examination these prove to be of little use. Instead one should consider making formula notes with sample question where the application part of formula is also addressed.

For example: In above formula acceleration  labeled as ‘a’ an usually taken in sense of something that increases speed but in examination one finds question on braking and would get confused about how sign should come.  Hence, in revision sheet, formula has to be mentioned in highlighted text as v2 = u2 +2as and below it question on braking should be described. In a nutshell, making these small changes in strategy during can make a lot of difference towards the result.

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