Jennifer is running the 100.0 m dash at track. She accelerates at a rate of 0.88 m/s2 for the first 45 m and then maintains this speed for the remainder of the race. How long will it take her to finish the race?

Question

Jennifer is running the 100.0 m dash at track.  She accelerates at a rate of 0.88 m/s2 for the first 45 m and then maintains this speed for the remainder of the race.  How long will it take her to finish the race?

Henry · Answer

d1 = 0.5a*T1^2 = 45 m. Solve for T1.
0.5*0.88*T1^2 = 45.
T1^2 = 102.3
T1 = 10.11 s. to run the 1st 45 m.

V = a*T1 = 0.88*10.11 = 8.9 m/s.

d2 = V*T2 = 8.9 * T2 = 100-45 = 55 m.
T2 = 55/8.9 = 6.18 s. To run the last 55
m.

T = T1+T2 = 10.11 + 6.18 = 16.29 s. to
run the race.