Answer:
Acceleration, a = 0.101 m/s²
Explanation:
Average speed = total distance / total time.
At the 7.43km mark, total distance = 7.43km or 7430m
Total time = 25 * 60 s = 1500s
Average speed = 7430m/1500s = 4.95m/s
He then covers (10 - 7.43)km = 2.57 km = 2570 m
in t = 27m43.6s - 25min = 2m43.6s = 163.6 s
Then he accelerates for 60 s, and maintains this velocity V, for the remaining (163.6 - 60)s = 103.6 s.
From V = u + at; V = 4.95m/s + a *60s
Distance covered while accelerating is
s = ut + ½at² = 4.95m/s * 60s + ½ a *(60s)² = 297m + a*1800s²
Distance covered while at constant velocity, v after accelerating is
D = velocity * time
Where v = 4.95m/s + a*60s
D = (4.95m/s + a*60s) * 103.6s = 512.82m + a*6216s²
Total distance covered after initial 7.43 km, S + D = 2570 m, so
2570 m = 297m + a*1800s² + 512.82m + a*6216s²
2570 = 809.82 + a*8016
a = 809.82m / 8016s² = 0.101 m/s²
