Sometimes it is convenient to construct a system of units so that all quantities can be expressed in terms of only one physical quantity. In one such system, dimensions of different quantities are given in terms of a quantity X as follows: [position] $=\left[X^\alpha\right]$; [speed ] $=\left[X^\beta\right]$; [acceleration ] $=\left[X^{\mathrm{P}}\right]$; $[$ linear momentum $]=\left[X^{\mathrm{q}}\right] ;[$ force $]=\left[X^{\mathrm{r}}\right]$. Then -
Select ALL correct options:
A
$\alpha+p=2 \beta$
B
$p+q-r=\beta$
C
$p-q+r=\alpha$
D
$p+q+r=\beta$
✓ Correct! Well done.
✗ Incorrect. Try again or view the solution.
⚠ Partially correct. Some answers are missing.
Solution
Sol. Given $\mathrm{L}=\mathrm{x}^\alpha$
$$
\begin{aligned}
& \mathrm{LT}^{-1}=\mathrm{x}^\beta \\
& \mathrm{LT}^{-2}=\mathrm{x}^{\mathrm{p}} \\
& \mathrm{MLT}^{-1}=\mathrm{x}^{\mathrm{q}} \\
& \mathrm{MLT}^{-2}=\mathrm{x}^{\mathrm{r}} \\
& \quad \frac{(1)}{(2)} \Rightarrow \mathrm{T}=\mathrm{x}^{\alpha-\beta}
\end{aligned}
$$
From (3)
$$
\begin{aligned}
& \frac{\mathrm{x}^\alpha}{\mathrm{x}^{2(\alpha-\beta)}}=\mathrm{x}^{\mathrm{p}} \\
\Rightarrow & \alpha+\mathrm{p}=2 \beta
\end{aligned}
$$
From (4)
$$
M=x^{q-\beta}
$$
From (5) $\Rightarrow x^q=x^r x^{\alpha-\beta}$
$$
\Rightarrow \alpha+r-q=\beta
$$
Replacing value ' $\alpha$ ' in equation (6) from (A)
$$
\begin{aligned}
& 2 \beta-\mathrm{p}+\mathrm{r}-\mathrm{q}=\beta \\
\Rightarrow & \mathrm{p}+\mathrm{q}-\mathrm{r}=\beta
\end{aligned}
$$
Replacing value of ' $\beta$ ' in equation (6) from (A)
$$
\begin{aligned}
& 2 \alpha+2 r-2 q=\alpha+p \\
& \alpha=p+2 q-2 r
\end{aligned}
$$
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