Problem 12.5

กำหนดให้ \(Δt_{1} = 0.80 s, Δt_{2} = 0.60 s\) และ \(Δx = 35 m\)

จาก \(v = \frac{\Delta r}{\Delta t}\)

\(v =\frac{2x}{\Delta t}; Δr = 2x\) เนื่องจากไปและกลับ

\(x =\frac{v\Delta t}{2}\)

\(\therefore x_{1} - x_{2} =\frac{v(\Delta t_{1} - \Delta t_{2})}{2}\)

\(\Delta x =\frac{v(\Delta t_{1} - \Delta t_{2})}{2}\)

\(\therefore \frac{x_{1}}{\Delta x}=\frac{\frac{v\Delta t_{1}}{2}}{\frac{v(\Delta t_{1} - \Delta t_{2})}{2}}\)

\(x_{1} =\frac{\Delta t_{1}\Delta x}{\Delta t_{1} - \Delta t_{2}}\)

\(x_{1} = 140 m \;\blacksquare\)