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Check by the method of dimensions, the formula ` upsilo = (1)/(lambda)sqrt((K)/(d)),` where `upsilon` is velocity of longitudinal waves, `lambdas` is wavelength of wave, K is coefficient of volume elasticity and d is density of the medium.

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To check the formula \( \upsilon = \frac{1}{\lambda} \sqrt{\frac{K}{d}} \) using the method of dimensions, we will follow these steps: ### Step 1: Identify the dimensions of each term in the formula. 1. **Velocity of longitudinal waves (\( \upsilon \))**: - The dimension of velocity is given by: \[ [\upsilon] = LT^{-1} \] 2. **Wavelength (\( \lambda \))**: - The dimension of wavelength is: \[ [\lambda] = L \] 3. **Coefficient of volume elasticity (\( K \))**: - The coefficient of volume elasticity is defined as volumetric stress divided by volumetric strain. - The dimension of stress (pressure) is: \[ [\text{Stress}] = \frac{[\text{Force}]}{[\text{Area}]} = \frac{MLT^{-2}}{L^2} = ML^{-1}T^{-2} \] - Since strain is dimensionless, we have: \[ [K] = ML^{-1}T^{-2} \] 4. **Density (\( d \))**: - The dimension of density is: \[ [d] = \frac{[\text{Mass}]}{[\text{Volume}]} = \frac{M}{L^3} = ML^{-3} \] ### Step 2: Substitute the dimensions into the right-hand side (RHS) of the formula. The RHS of the formula is: \[ \frac{1}{\lambda} \sqrt{\frac{K}{d}} \] 1. Substitute the dimensions: - The dimension of \( \frac{1}{\lambda} \) is: \[ \left[\frac{1}{\lambda}\right] = L^{-1} \] - Now, calculate the dimensions of \( \frac{K}{d} \): \[ \frac{K}{d} = \frac{ML^{-1}T^{-2}}{ML^{-3}} = \frac{L^{3}}{L^{-1}}T^{-2} = L^{2}T^{-2} \] - Taking the square root: \[ \sqrt{\frac{K}{d}} = \sqrt{L^{2}T^{-2}} = LT^{-1} \] 2. Combine the dimensions: - Now, multiply \( \frac{1}{\lambda} \) and \( \sqrt{\frac{K}{d}} \): \[ \left[\frac{1}{\lambda} \sqrt{\frac{K}{d}}\right] = L^{-1} \cdot LT^{-1} = T^{-1} \] ### Step 3: Compare the dimensions of the left-hand side (LHS) and the right-hand side (RHS). - The dimension of the LHS (\( \upsilon \)): \[ [\upsilon] = LT^{-1} \] - The dimension of the RHS: \[ \left[\frac{1}{\lambda} \sqrt{\frac{K}{d}}\right] = LT^{-1} \] ### Conclusion: Since the dimensions of the LHS and RHS are different, the formula \( \upsilon = \frac{1}{\lambda} \sqrt{\frac{K}{d}} \) is dimensionally incorrect.
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