# physics

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An 18-year-old runner can complete a 10.0-km course with an average speed of 4.53 m/s. A 50-year-old runner can cover the same distance with an average speed of 3.91 m/s. How much later (in seconds) should the younger runner start in order to finish the course at the same time as the older runner?

• physics -

t1=s/v1=10000/4.53 = 2207.5 s
t2 = s/v2 = 10000/3.91 = 2557.5 s.
Δt= t2-t1= 2557.5- 2207.5= 350 s =5.83 min

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