Which of the following is a standard unit for measuring pressure?

Which of the following is a standard unit for measuring pressure?

• A. Pascals (Pa), atmospheres (atm), torr, and millimeters of mercury (mmHg)
• B. Celsius, Kelvin, Fahrenheit, Rankine
• C. Newtons (N), joules (J), watts (W), volts (V)
• D. Liters, cubic meters, gallons, pints

Answer: (A)

Pressure is defined as force per unit area, so its standard unit is the pascal (Pa), which is one newton per square meter (N/m^2). In practice, other widely used pressure units are also accepted: atmospheres (atm) and the units Torr and millimeters of mercury (mmHg). By convention, 1 atm equals 101,325 Pa and is also defined as 760 Torr or 760 mmHg. This means Pascals, atmospheres, Torr, and mmHg are all standard for expressing pressure. The other options mix different physical quantities: temperature scales (Celsius, Kelvin, Fahrenheit, Rankine) measure temperature, not pressure; and the remaining units (newtons, joules, watts, volts) correspond to force, energy, power, and electric potential, not pressure. So the first set correctly captures standard pressure units.

Pressure is defined as force per unit area, so its standard unit is the pascal (Pa), which is one newton per square meter (N/m^2). In practice, other widely used pressure units are also accepted: atmospheres (atm) and the units Torr and millimeters of mercury (mmHg). By convention, 1 atm equals 101,325 Pa and is also defined as 760 Torr or 760 mmHg. This means Pascals, atmospheres, Torr, and mmHg are all standard for expressing pressure.

The other options mix different physical quantities: temperature scales (Celsius, Kelvin, Fahrenheit, Rankine) measure temperature, not pressure; and the remaining units (newtons, joules, watts, volts) correspond to force, energy, power, and electric potential, not pressure. So the first set correctly captures standard pressure units.