Velocity (v) and acceleration (a) in two systems of units 1 and 2 are related as
\(v_2=\frac{n}{m^2}v_1\) and \(a_2=\frac{a_1}{mn}\)
respectively. Here m and n are constants. The relations for distance and time in two systems respectively are :
\(\frac{n^3}{m_3}L_1=L_2\) and\(\frac{n^2}{m}T_1=T_2\)
\(L_1=\frac{n^4}{m^2}L_2\) and \(T_1=\frac{n^2}{m}T_2\)
\(L_1=\frac{n^2}{m}L_2\) and \(T_1=\frac{n^4}{m^2}T_2\)
\(\frac{n^2}{m}L_1=L_2 \) and \(\frac{n^4}{m^2}T_1=T_2\)
The correct answer is (A) : \(\frac{n^3}{m^3}L_1=L_2\) and \(\frac{n^2}{m}T_1=T_2\)
\([L]=\frac{[v^2]}{[a]}\)
so
\(\frac{[v_2]^2}{[a_2]}=\frac{[\frac{n}{m^2}v_1]^2}{[\frac{a_1}{mn}]}\)
\(\frac{[v_2]^2}{[a_2]}=\frac{n^3}{m^3} \frac{[v_1]^2}{[a_1]}\)
or \([L_2]=\frac{n^3}{m^3}[L_1]\)
Similarly
\([T]=\frac{[v]}{[a]}\)
So,
\([T_2]=\frac{n^2}{m}[T1]\)
Match List-I with List-II.
Choose the correct answer from the options given below :
A temperature difference can generate e.m.f. in some materials. Let $ S $ be the e.m.f. produced per unit temperature difference between the ends of a wire, $ \sigma $ the electrical conductivity and $ \kappa $ the thermal conductivity of the material of the wire. Taking $ M, L, T, I $ and $ K $ as dimensions of mass, length, time, current and temperature, respectively, the dimensional formula of the quantity $ Z = \frac{S^2 \sigma}{\kappa} $ is:
A quantity \( X \) is given by: \[ X = \frac{\epsilon_0 L \Delta V}{\Delta t} \] where:
- \( \epsilon_0 \) is the permittivity of free space,
- \( L \) is the length,
- \( \Delta V \) is the potential difference,
- \( \Delta t \) is the time interval.
The dimension of \( X \) is the same as that of:
Let $ f: \mathbb{R} \to \mathbb{R} $ be a twice differentiable function such that $$ f''(x)\sin\left(\frac{x}{2}\right) + f'(2x - 2y) = (\cos x)\sin(y + 2x) + f(2x - 2y) $$ for all $ x, y \in \mathbb{R} $. If $ f(0) = 1 $, then the value of $ 24f^{(4)}\left(\frac{5\pi}{3}\right) $ is:
Dimensional Analysis is a process which helps verify any formula by the using the principle of homogeneity. Basically dimensions of each term of a dimensional equation on both sides should be the same.
Limitation of Dimensional Analysis: Dimensional analysis does not check for the correctness of value of constants in an equation.
Let us understand this with an example:
Suppose we don’t know the correct formula relation between speed, distance and time,
We don’t know whether
(i) Speed = Distance/Time is correct or
(ii) Speed =Time/Distance.
Now, we can use dimensional analysis to check whether this equation is correct or not.
By reducing both sides of the equation in its fundamental units form, we get
(i) [L][T]-¹ = [L] / [T] (Right)
(ii) [L][T]-¹ = [T] / [L] (Wrong)
From the above example it is evident that the dimensional formula establishes the correctness of an equation.