To qualify for the finals in a racing event, a race car must achieve an average

Question

To qualify for the finals in a racing event, a race car must achieve an average speed of 245 km/h on a track with a total length of 1800 m. If a particular car covers the first half of the track at an average speed of 222 km/h, what minimum average speed must it have in the second half of the event in order to qualify? To qualify for the finals in a racing event, a race car must achieve an average speed of 245 km/h on a track with a total length of 1800 m. If a particular car covers the first half of the track at an average speed of 222 km/h, what minimum average speed must it have in the second half of the event in order to qualify?

Explanation / Answer

here,

let the time taken for first half be t1 and the time taken for seccond half be t2

average speed , vavg = 245 km/h

vavg = 68.06 m/s

total length , s = 1800 m

speed for first half , v1 = 222 km/h

v1 = 61.67 m/s

let the speed for seccond half be v2

average speed = total distance travelled/ total time taken

vavg = s/(s/2v1 + s/2v2)

68.06 = 1800/ (900/61.67 + 900/v2)

solving for v2

v2 = 75.93 m/s

the average speed for seccond half must be 75.93 m/s

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