MCQ
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 $]=\left[X^{ p }\right]$; [linear momentum $]=\left[X^{ q }\right]$; [force $]=\left[X^{ I }\right]$. Then -

$(A)$ $\alpha+p=2 \beta$

$(B)$ $p+q-r=\beta$

$(C)$ $p-q+r=\alpha$

$(D)$ $p+q+r=\beta$

  • $A,B$
  • B
    $A,C$
  • C
    $A,D$
  • D
    $B,C$

Answer

Correct option: A.
$A,B$
a
Given $L =x^\alpha$     $. . . . . . (1)$

$LT ^{-1}=x^\beta$        $. . . . . . (2)$

$LT ^{-2}=x^{ p }$          $. . . . . . (3)$

$MLT ^{-1}=x^q$           $. . . . . . (4)$

$MLT ^{-2}=x^{ I }V$     $. . . . . . (5)$

$\quad \frac{(1)}{(2)} \Rightarrow T =x^{\alpha-\beta}$

From $(3)$

$\frac{ x ^\alpha}{ x ^{2(\alpha-\beta)}}= x ^{ p }$

$\Rightarrow \alpha+ p =2 \beta$

From $(4)$

$M=x^{q-\beta}$

From $(5)$ $\Rightarrow x ^{ q }= x ^{ T } x ^{\alpha-\beta}$

$\Rightarrow \alpha+ r - q =\beta$

Replacing value ' $\alpha$ ' in equation $(6)$ from $(A)$

$2 \beta- p + r - q =\beta$

$\Rightarrow  p + q - r =\beta$

Replacing value of ' $\beta$ ' in equation $(6)$ from $(A)$

$2 \alpha+2 r-2 q=\alpha+p$

$\alpha=p+2 q-2 r$

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$X=\frac{3}{2} R \ln \left(\frac{T}{T_A}\right)+R \ln \left(\frac{V}{V_A}\right)$. Here, $R$ is gas constant, $V$ is volume of gas, $T_A$ and $V_A$ are constants.

The $List-I$ below gives some quantities involved in a process and $List-II$ gives some possible values of these quantities.

List-$I$ List-$II$
$(I)$ Work done by the system in process $1 \rightarrow 2 \rightarrow 3$ $(P)$ $\frac{1}{3} R T_0 \ln 2$
$(II)$ Change in internal energy in process $1 \rightarrow 2 \rightarrow 3$ $(Q)$ $\frac{1}{3} RT _0$
$(III)$ Heat absorbed by the system in process $1 \rightarrow 2 \rightarrow 3$ $(R)$ $R T _0$
$(IV)$ Heat absorbed by the system in process $1 \rightarrow 2$ $(S)$ $\frac{4}{3} RT _0$
  $(T)$ $\frac{1}{3} RT _0(3+\ln 2)$
  $(U)$ $\frac{5}{6} RT _0$

If the process carried out on one mole of monatomic ideal gas is as shown in figure in the PV-diagram with $P _0 V _0=\frac{1}{3} RT _0$, the correct match is,

$(1)$$I \rightarrow Q, II \rightarrow R , III \rightarrow P , IV \rightarrow U$

$(2)$ $I \rightarrow S , II \rightarrow R , III \rightarrow Q , IV \rightarrow T$

$(3)$ $I \rightarrow Q , II \rightarrow R , III \rightarrow S , IV \rightarrow U$

$(4)$ $I \rightarrow Q , II \rightarrow S , III \rightarrow R , IV \rightarrow U$

($2$) If the process on one mole of monatomic ideal gas is an shown is as shown in the $TV$-diagram with $P _0 V _0=\frac{1}{3} RT _0$, the correct match is

$(1)$ $I \rightarrow S, II \rightarrow T, III \rightarrow Q , IV \rightarrow U$

$(2)$ $I \rightarrow P , II \rightarrow R, III \rightarrow T , IV \rightarrow S$

$(3)$ $I \rightarrow P, II \rightarrow, III \rightarrow Q, IV \rightarrow T$

$(4)$ $I \rightarrow P, II \rightarrow R, III \rightarrow T, IV \rightarrow P$

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