What is defined as the force that accelerates a mass of one kilogram at the rate of one meter per second squared?

The correct answer is defined as the force that accelerates a mass of one kilogram at the rate of one meter per second squared is known as a Newton. This definition is rooted in Newton's second law of motion, which states that force equals mass times acceleration (F = ma). Therefore, if you have a mass of 1 kilogram and you want to accelerate it at 1 meter per second squared, the force required to achieve that is precisely 1 Newton.

Other terms like Joule, Pascal, and Watt refer to different physical quantities. A Joule is a unit of energy, a Pascal measures pressure, and a Watt quantifies power. Each of these concepts is essential in physics, but they do not describe the relationship between mass and acceleration that is captured by the Newton. Hence, the Newton is specifically the force unit in the International System of Units that aligns directly with the definition provided in the question.