Force is defined as the interaction that causes an object to change its velocity, and it is measured in Newtons (N) in the International System of Units (SI). One Newton is defined as the amount of force required to accelerate a one-kilogram mass by one meter per second squared. Other units listed, such as Joules, Watts, and Volts, pertain to energy, power, and electrical potential, respectively, making Newton the appropriate unit for measuring force.