How to solve Numerical problem in physics?

 

How to solve Numerical problem in physics?

“Start walking. The path will become clearer”

 Step 1: Translating from English language to Maths and Drawing.

·        Nature is written in the language of Mathematics. Drawing is the language of Engineers and Scientists.

·        Read the question line by line converting it into a simple cartoon diagram or a mathematical expression. Mark the numerical values in appropriate places in the diagram or with the mathematical notations.

 Step 2: Understand what is given and what is to be found.

 Step 3: Think about the question and its related concepts, guiding principles, equations, formulas etc.

·        Final formulas in the derivations may be difficult to remember whereas the underlying guiding principle from which those formulas were derived may be easier to remember.

·        Eg. If orbital velocity of a satellite is asked, instead of remembering the final formula for $v_o$ it is much logical and meaningful to start with the underlying guiding principle.

\[Centripetal force = Gravitational Force\]

\[\frac{mv_o^2}{r}=\frac{GMm}{r}\]

Step 4: Apply the numerical values and simplify the results.

·        For competitive exams calculators and log tables are not allowed. Take approximate close values for the decimal point values and simplify them.

·        Do not waste your valuable time simplifying intermediate expressions, just take it to the next step and it may cancel out easily.

\[\pi\approx\frac{22}{7}\hspace{20mm}\pi\approx3\hspace{20mm}\pi^2\approx10\]

Step 5: Reality check. Ask yourself if the answer makes sense. Otherwise double check the working to locate the error.

·        Eg. Can the speed of a car be 1000 km/h, can the speed of an airplane be 2 km/h, can the rise in temperature in an experiment be 23000 degree Celsius, can the refractive index of medium be less than 1, can the absolute temperature Kelvin be in negative.

SI units to be used in the formulas and answers to be given in appropriate units.