Train stops

Without stoppages, the speed of a train is 150 km/h and with stoppages, it is 100 km/h. How many minutes, does the train stop?

Solve for distance 300 km.

Correct answer:

t =  60 min

Step-by-step explanation:

$$\begin{gathered} v_1=150\text{km/h} \\ {v}_2=100\text{km/h} \\ {v}_1=s/t_1 \\ {v}_2=s/t_2 \\ {t}_2=t_1+t \\ {v}_1\cdot t_1=s \\ {v}_2\cdot t_2=s \\ {v}_1\cdot t_1=v_2\cdot (t_1+t) \\ s=300\text{km} \\ {t}_1=s/v_1=300/150=2\text{h} \\ {t}_2=s/v_2=300/100=3\text{h} \\ \Delta t=t_2-t_1=3-2=1\text{h} \\ t=h_2\min (\Delta t)=h_2\min (1)=60\text{min} \end{gathered}$$

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