What unit is commonly used to measure force in the International System (SI)?

• A. Newton
• B. Pound
• C. Joule
• D. Pascal

Answer: (A)

The Newton is the standard unit of force in the International System of Units (SI). It is defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared. This definition ties closely to Newton's second law of motion, which states that force is equal to mass times acceleration (F=ma).

The pound, while a unit of force used primarily in the United States customary system, is not part of the SI system. The joule is a unit of energy, which also relates to force but is not a direct measurement of it. The pascal is a unit of pressure, defined as one newton per square meter, but again does not measure force directly. Thus, the Newton is the appropriate and correct unit to use when measuring force in SI.