A swimmer is 1.8 meters tall. She dives into the pool and swims her race with a constant acceleration of .25m/^2. How long does it take her to pass the backstroke flags that are 20 meters away?
When I did it, i got 13.2 seconds. Could someone who is good at physics please check it and see if i did it wrong? Thanks so much.
2007-01-25 12:30:47 · 6 answers · asked by Jane A 3 in Science & Mathematics ➔ Physics
I ment to say .25m/s^2!
2007-01-25 12:31:27 · update #1
you are correct, and elizabeth is lame
2007-01-25 12:37:43 · answer #1 · answered by Anonymous · 0⤊ 0⤋
A swimmer has to swim the distance 20 m + 1.8 m = 21.8 m, in order to pass the flags (it is because she dives verticaly, I assume, at the edge of the pool and so she has to swim 20 m plus her own height)
One of the kinematics equations for uniformly accelerated motion is:
s = 1/2 x a x t2
If you solve for t, you get:
t = sqrt (2 x s / a) = 13.2 s ---> you were probably right!
2007-01-25 12:50:30 · answer #2 · answered by Dorian36 4 · 0⤊ 0⤋
You never told the answer so I don't know if I got it right, but I got 12.1s. I think you may have to account for her height by subtracting it form the total distance to get 18.2m instead of 20.
2007-01-25 12:50:47 · answer #3 · answered by The Q-mann 3 · 1⤊ 1⤋
No. First of all, you can't use d=vt when there is acceleration. (Your distance would have been the distance the car travelled if it kept that speed up for THE WHOLE TIME.) Second, the acceleration formula is (v2-vo)/t (not over d). For part a, use d=vot+1/2at^2.
2016-05-24 00:09:32 · answer #4 · answered by ? 4 · 0⤊ 0⤋
I made it 12.1s. You have to account for her height by subtracting it form the total distance to get 18.2m instead of 20m.
2007-01-25 12:36:34 · answer #5 · answered by epbr123 5 · 0⤊ 1⤋
physics is lame =]
2007-01-25 12:36:13 · answer #6 · answered by Anonymous · 0⤊ 1⤋