Question

1 Poise is equal to

• A. \(1\ \mathrm{Ns/m^2}\)
• B. \(0.1\ \mathrm{Ns/m^2}\)
• C. \(10\ \mathrm{Ns/m^2}\)
• D. \(0.01\ \mathrm{Ns/m^2}\)

Hint:

Useful viscosity conversions: \[ \boxed{ 1\ \text{Poise} = 0.1\ \mathrm{Pa\cdot s} = 0.1\ \mathrm{N\,s/m^2} } \] Also, \[ \boxed{ 1\ \text{centipoise}=10^{-3}\ \mathrm{Pa\cdot s}. } \]

Answer 1

The Correct Option is B

Step 1: Recall the SI conversion of Poise. The CGS unit of dynamic viscosity is \[ \boxed{1\ \text{Poise}=1\ \text{g cm}^{-1}\text{s}^{-1}.} \]

Step 2: Convert into SI units. Using \[ 1\ \text{g}=10^{-3}\ \text{kg}, \] and \[ 1\ \text{cm}=10^{-2}\ \text{m}, \] we obtain \[ 1\ \text{Poise} = \frac{10^{-3}}{10^{-2}} \frac{\text{kg}}{\text{m}\cdot\text{s}} = 10^{-1} \frac{\text{kg}}{\text{m}\cdot\text{s}}. \] Since \[ 1\ \frac{\text{kg}}{\text{m}\cdot\text{s}} = 1\ \mathrm{N\,s/m^2}, \] therefore, \[ \boxed{ 1\ \text{Poise} = 0.1\ \mathrm{N\,s/m^2}. } \] Hence, \[ \boxed{0.1\ \mathrm{N\,s/m^2}} \] is the correct answer. Thus, \[ \boxed{(B)} \] is the correct answer.