With area fixed, the normal stress follows the force. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Keep the area fixed before changing force

This contrast holds the area marker steady. Only the force input is larger than the base case.

F=24 NA=3 m2F=24\ \text{N}\qquad A=3\ \text{m}^{2}
Fixed-area force contrastOnly the force vector changes in this case.forceareaforce=24 Narea=3 m^2stress=8 Pa

Doubling force doubles stress in the table

The area column is unchanged. The force and stress columns scale together in exact integer steps.

FAσ12 N3 m24 Pa24 N3 m28 Pa36 N3 m212 Pa\begin{array}{c|c|c}F&A&\sigma\\12\ \text{N}&3\ \text{m}^{2}&4\ \text{Pa}\\24\ \text{N}&3\ \text{m}^{2}&8\ \text{Pa}\\36\ \text{N}&3\ \text{m}^{2}&12\ \text{Pa}\\\end{array}

Doubling force doubles the stress when area stays fixed

The area is unchanged, so the checked stress doubles with the force.

σ=24 N3 m2=8 Pa\sigma=\frac{24\ \text{N}}{3\ \text{m}^{2}}=8\ \text{Pa}
Double-force stress ledgerOnly the force changes in this contrast case.forceareaforce=24 Narea=3 m^2stress=8 Pa