1.

If force (F). velocity (V) and time (T) are taken asfundamental units, then the dimensions of massare[AIPMT-2014](1) [F V T-](2) [F VT(3) [FV-T'(4) [F V-T]​

Answer»

\maltese \: \underline{\sf AnsWer :} \: \maltese \\

\dashrightarrow\:\:\sf m \propto [F]^{x}  \: [V]^{y} \:  [T]^{z} \\

By adding 'k' as a proportionality constant we get :

\dashrightarrow\:\:\sf m  = k \:  [F]^{x}  \: [V]^{y} \:  [T]^{z} \\

\\\bullet\textsf{ Dimensions of mass (m) =\textbf{[M$^ \text1$L$^ \text0$T$^ \text0$]}} \\

\bullet\textsf{ Dimensions of force (F) = [M] [LT$^{ \text{-2}}$]  =  \textbf{[MLT$^{ \text{-2}}$]}} \\

\bullet\textsf{ Dimensions of velocity (V) = $\dfrac{ \text{[L]}}{ \text{[T]}}$ =  \textbf{[M$^\text0$LT$^{ \text{-1}}$]}} \\

\bullet\textsf{ Dimensions of Time Period (T) =\textbf{[M$^ \text0$L$^ \text0$T$^ \text1$]}}\\  \\

\dashrightarrow\:\:\sf [M^1 L^0 T^0] =   [M^1 L^1 T^{-2}]^{x}  \: [M^0 L^1 T^{-1}]^{y} \:  [M^0 L^0 T^1]^{z} \\

\dashrightarrow\:\:\sf [M^1 L^0 T^0] =   [M]^{x}  \: [ L]^{x + y} \:  [T]^{ - 2x - y + z} \\

Now, on COMPARING the POWERS of LHS and RHS we get :

\longrightarrow\:\:\sf x = 1  \qquad \qquad...(i)\\

\longrightarrow\:\:\sf x + y = 0 \\

From equation (i) Substituting x = 1 in above equation we get :

\longrightarrow\:\:\sf 1 + y = 0 \\

\longrightarrow\:\:\sf y =  - 1 \qquad \qquad.... (ii)

\longrightarrow\:\:\sf  - 2x - y + z = 0 \\

From equation (i) and (ii) Substituting the VALUE of x and y in above equation:

\longrightarrow\:\:\sf  - 2(1) - ( -1 ) + z = 0 \\

\longrightarrow\:\:\sf  - 2  + 1  + z = 0 \\

\longrightarrow\:\:\sf  - 2  + 1  =  - z\\

\longrightarrow\:\:\sf  - 1  =  - z\\

\longrightarrow\:\:\sf  z = 1\\

Hence, our FINAL answer will be :

\dashrightarrow\:\: \underline{ \boxed{\frak{m =  [F]^{1}  \: [V]^{-1} \:  [T]^{1}}}} \\

Hence,the OPTION (4) is correct answer.



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