Runners lapping

Two runners run on a 3200 m oval track, one running at 12 km/h and the other at 8 km/h. How long does it take for the first runner to finish the second one?

Final Answer:

t =  0.8 h

Step-by-step explanation:

$$\begin{gathered} s=3200/1000=\frac{16}{5}=3.2 \\ {v}_1=12 \\ {v}_2=8 \\ d=v_1-v_2=12-8=4 \\ t=s/d=3.2/4=\frac{4}{5}=0.8=0.8\text{h} \\ {t}_2=60\cdot t=60\cdot 0.8=48 \end{gathered}$$

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