Physics - Unit & Dimension Question with Solution | TestHub

Physics is a science that deals with practical life. As such, in most situations, we are not concerned with exact values but approximate values. While studying theory, we often deal with approximations that can be taken to nearly represent real situations. Rigorous analysis has shown that a given approximation can be said to be correct if the error in the quantity concerned is less than or equal to 5%.

The error is defined as:

$$\delta =\frac{A_{ideal}-A_{real}}{A_{ideal}}\times 100$$

$A_{ideal}$ is the value of the quantity in an ideal situation, and $A_{real}$ is the value of the quantity in a real situation. For example, we say that the center of mass of a semicircular ring is at $\frac{2R}{\pi }$. This $\frac{2R}{\pi }$ is $A_{ideal}$. But in reality, a ring is an annular disc. Its center of mass can be found to be at $\frac{4(R_1^2+R_1{R}_2+R_2^2)}{3\pi (R_1+R_2)}$. This is $A_{real}$. In a given situation, we can find the error in the estimation of the center of mass of the ring.