Question

A sprinter accelerates at 4 m/s2 for 3 seconds, and then runs the rest of the race at a constant speed. If the race is 100 m, how much time does the sprinter take to fi nish the race?
1/2(acceleration)(time^2)=distance
1/2(4 m/s^2)(3s)^2= 18m

100m-18m= 82m (total distance remaining)
Time= Distance/speed
Time= 82m/12m/s = 6.83s

Time= 6.83s + 3s= 9.83s

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