C.Spring scales and kinematics measurements (rulers and clocks) together establish the first law
suppose that. in an inertial frame. measurements with rulers and clocks yield that the acceleration (a) of an object is zero.Simultaneous measurements using spring scales yield that the total force (F) on the object is zero. Thus, together the two approaches have established the first law. Because (a) is measured to a part in 1044, and (F) to a part in 1033, the first law is established to a part in 1033. Note that if we plot |a| vs |F| the first law gives only the intercept of the plot; this does not forbid a dependence on |F| that is more complex than linear (e.g., quadratic, cubic, or linear plus quadratic).