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March 2, 2015

March 2, 2015

Posted by **Chloe** on Sunday, January 11, 2009 at 11:35pm.

I got 4.9 seconds for the first one and I do not get the last one. Thanks Y'all.

- Physics -
**Damon**, Monday, January 12, 2009 at 5:50am84 km/hr *(1000m/km) /(3600 s/hr)= 23.3 m/s

24 km/hr = 6.67 m/s

d fast train = d

d slow train = d-47

d fast train= d = 23.3 t - .5(2.1) t^2

d slow train = (d-47) = 6.67 t

so

23.3 t - 1.05 t^2 = 6.67 t + 47

1.05 t^2 - 16.6 t + 47 = 0

approximate

2t = 26.6 +/- sqrt (276-188)

2 t = 26.6 +/- 9.4

2t = 36 or 17.2

t = 18 or 8.8

the 8.8 is the first overtaking, the 18 is when the slow one then catches up with the fast one again after it really slows down (assuming they are actually on parallel tracks and do not crash)

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