Please help me find the answer i have nooo idea how to do ts Imagine that Usain Bolt can reach s maximum speed in 1.7 s. What should be s maximum speed in order to tie the 19.5-s record for the 200-m das
Answers
this question is tricky because we would have to use formula in formula
formulas {
Vi - initial velocity
Vf - final velocity
x - distance
t - time
a - acceleration
x = Vi*t + 1/2*a*t^2 in this case
a = (Vf - Vi) / t because Vi = 0 we can use short cut a = V/t
}
Vi = 0 (because "Imagine that Usain Bolt can reach s maximum speed in 1.7 s" that mean he started from 0m/s)
t = 1.7 (time it takes to reach his max speed)
delta x (distance) =200m
t =19.5 - (this time saying that he need to do 200m in 19.5 sec)
Vf =
we need to split 200 m dash into two parts.
First part he is accelerating steadily from 0 m/s to his maximum speed v over the first 1.7 (we need to find distance x )
Second part he maintains speed v for the remaining 17.8 seconds, arriving at the finish line at 19.5 seconds. 200-x
In First part we need to find what distance it took him to reach his max speed, we now that it took him 1.7 sec. Δx=1/2 * a * t^2 now we dont now a but we can plug in formula a = v / 1.7 and this will lead to Δx = 1/2 * v/1.7 * 1.7^2 we can simplify 1.7 and 1.7^2 Δx = (v * 1.7)/2 Δx = 0.85v
we found first distance now we plug it in second because we now that distance of acceleration is 0.85v now we plug it in 200 -x /t
Δt = (time it need to take to finish whole race) - (time it was accelerating) =
= 19.5 - 1.7 = 17.8
v = (200 - 0.85v) / 17.8 (devide by time left)
18.65v = 200 we dived both side by 18.65
v = 10.72 m/s <== your answer
hope this help!!!!1