Kilometers 82735

Fifteen kilometers in front of us, a car travels at a speed of 70 km/h. We drive at an average speed of 100 km/h. How many minutes will it take us to catch up with the car?

Correct answer:

t =  30 min

Step-by-step explanation:

$$\begin{gathered} s_1=15\text{km} \\ {v}_1=70\text{km/h} \\ {v}_2=100\text{km/h} \\ {s}_1+v_1\cdot t=v_2\cdot t \\ {s}_1+v_1\cdot T=v_2\cdot T \\ 15+70\cdot T=100\cdot T \\ 30T=15 \\ T=\frac{15}{30}=0.5 \\ T=\frac{1}{2}=0.5 \\ t=T\to \text{min}=T\cdot 60\text{min}=0.5\cdot 60\text{min}=30\text{min}=30\text{min} \end{gathered}$$

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