In introductory kinematics, how do you find the magnitude of the average acceleration of an object over a time interval $\Delta t$, given its initial velocity $v_{\mathrm{i}}$ and final velocity $v_{\mathrm{f}}$ in one dimension?

• A. $a=\frac{\Delta t}{v_{\mathrm{f}}-v_{\mathrm{i}}}$.
• B. $a=v_{\mathrm{f}}-v_{\mathrm{i}}$.
• C. $a=\frac{v_{\mathrm{f}}-v_{\mathrm{i}}}{\Delta t}$ and the magnitude is $\left|a\right|$.
• D. $a=\frac{v_{\mathrm{f}}+v_{\mathrm{i}}}{\Delta t}$.

Answer: (C)