r = 225km/h = 225000/3600s = 62.5 m/s. = Average speed for full length.
r1 = 205km/h = 205000m/3600s = 56.94 m/s.= Average speed for 1st half(700m).
(r1+r2)/2 = r
(56.94+r2)/2 = 62.5 m/s.
56.94 + r2 = 125
r2 = 125-56.94 = 68.06 m/s = Average speed for 2nd half of race.
To qualify for the finals in a racing event, a race car must achieve an average speed of 225 km/h on a track with a total length of 1.4 km. If a particular car covers the first half of the track at an average speed of 205 km/h, what minimum average speed must it have in the second half to be able to qualify for the event?
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