A microbar is equal to which of the following?

A microbar is equal to which of the following?

• A. 1 dyne per square centimeter
• B. 1 pascal
• C. 1 newton per square meter
• D. 1 erg per cubic centimeter

Answer: (A)

Understanding pressure units and how to switch between systems helps here. A microbar is 10^-6 of a bar. Since 1 bar equals 100,000 pascals, a microbar equals 0.1 pascal. Because 1 pascal is 1 newton per square meter, 0.1 pascal is 0.1 N/m^2. To express that in the CGS unit dyn/cm^2, use the conversions 1 N = 10^5 dyn and 1 m^2 = 10^4 cm^2, so 1 N/m^2 = 10 dyn/cm^2. Therefore 0.1 N/m^2 = 1 dyn/cm^2. So a microbar is equal to 1 dyn/cm^2. The other units (1 pascal, 1 N/m^2, or erg/cm^3) describe the same magnitude in different systems, but the direct CGS pressure unit matching a microbar is dyn/cm^2.

Understanding pressure units and how to switch between systems helps here. A microbar is 10^-6 of a bar. Since 1 bar equals 100,000 pascals, a microbar equals 0.1 pascal. Because 1 pascal is 1 newton per square meter, 0.1 pascal is 0.1 N/m^2. To express that in the CGS unit dyn/cm^2, use the conversions 1 N = 10^5 dyn and 1 m^2 = 10^4 cm^2, so 1 N/m^2 = 10 dyn/cm^2. Therefore 0.1 N/m^2 = 1 dyn/cm^2. So a microbar is equal to 1 dyn/cm^2. The other units (1 pascal, 1 N/m^2, or erg/cm^3) describe the same magnitude in different systems, but the direct CGS pressure unit matching a microbar is dyn/cm^2.