NEET
- Exam
- NEET
- Subject
- Physics
- Chapter
- Units and Dimensions
NEET · Physics · Units and Dimensions
The displacement y of a particle at position x and time t is given...
The displacement of a particle at position and time is given by the equation . If Force (), Density (), and Time () are chosen as the fundamental physical quantities, what are the dimensions of the quantity ?
Options
- A
- B
- C
- D
Correct answer
C.
Step-by-step solution
According to the principle of dimensional homogeneity, the arguments of trigonometric functions must be dimensionless. Thus, the quantities are dimensionless.
Since represents displacement, .
The dimensional formula for the required quantity is:
\left[\dfrac{AB}{C}\right] = \dfrac{[L][T^{-1}]}{[L^{-1}]} = [L^2 T^{-1}][L^2 T^{-1}] = [F]^a [\rho]^b [T]^c[MLT^{-2}][ML^{-3}][T][M^0 L^2 T^{-1}] = [MLT^{-2}]^a [ML^{-3}]^b [T]^c[M^0 L^2 T^{-1}] = [M^{a+b} L^{a-3b} T^{-2a+c}]MLTa + b = 0 \Rightarrow b = -aa - 3b = 2-2a + c = -1b = -aa - 3(-a) = 2 \Rightarrow 4a = 2 \Rightarrow a = \dfrac{1}{2}b = -\dfrac{1}{2}a = \dfrac{1}{2}-2\left(\dfrac{1}{2}\right) + c = -1 \Rightarrow -1 + c = -1 \Rightarrow c = 0\dfrac{AB}{C}[F^{1/2} \rho^{-1/2} T^0][F^{1/2} \rho^{-1/2} T^0]
Since represents displacement, .
The dimensional formula for the required quantity is:
\left[\dfrac{AB}{C}\right] = \dfrac{[L][T^{-1}]}{[L^{-1}]} = [L^2 T^{-1}][L^2 T^{-1}] = [F]^a [\rho]^b [T]^c[MLT^{-2}][ML^{-3}][T][M^0 L^2 T^{-1}] = [MLT^{-2}]^a [ML^{-3}]^b [T]^c[M^0 L^2 T^{-1}] = [M^{a+b} L^{a-3b} T^{-2a+c}]MLTa + b = 0 \Rightarrow b = -aa - 3b = 2-2a + c = -1b = -aa - 3(-a) = 2 \Rightarrow 4a = 2 \Rightarrow a = \dfrac{1}{2}b = -\dfrac{1}{2}a = \dfrac{1}{2}-2\left(\dfrac{1}{2}\right) + c = -1 \Rightarrow -1 + c = -1 \Rightarrow c = 0\dfrac{AB}{C}[F^{1/2} \rho^{-1/2} T^0][F^{1/2} \rho^{-1/2} T^0]