Two people

Two straight lines cross at right angles. Two people start simultaneously at the point of intersection. John walking at the rate of 4 kph in one road, Jenelyn walking at the rate of 8 kph on the other road. How long will it take for them to be 20√5 km apart

Correct result:

t =  5 h

Solution:

$$\begin{gathered} v_1=4\text{ km/h } \\ {v}_2=8\text{ km/h } \\ s=20\cdot \sqrt{5}=20\sqrt{5}\text{ km}\doteq 44.7214\text{ km } \\ v=\sqrt{v_1^2+v_2^2}=\sqrt{4^2+8^2}=4\sqrt{5}\text{ km/h}\doteq 8.9443\text{ km/h } \\ t=s\mathrm{/}v=44.7214\mathrm{/}8.9443=5\text{ h} \end{gathered}$$

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Showing 1 comment:

Dr Math

checkout also our speed/velocity calculator:

https://www.hackmath.net/en/calculator/conversion-of-speed-units?a=8+kph&submit=Convert&dir=0

2 years ago  Like

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