- #1
P944
- 9
- 0
Homework Statement
To find the height of an overhead power line, you throw a ball straight upward. The ball passes the line on the way up after 0.85 s, and passes it again on the way down 1.2 s after it was tossed.
(a) What is the height of the power line?
(b) What is the initial speed of the ball?
Homework Equations
v = v0 + at
x=x0+v0*t + 1/2*a*t^2
x = x0 +v*t - 1/2*a*t^2
v^2 = v0^2 +2*a*(x-x0)
The Attempt at a Solution
I drew a picture and decided to solve for intial speed first. I used the equation v = v0 + a* t . V=0, a = -9.8m/s^2 and i took time at v0 to be 1.25 + 0.85/2 = 1.05 s
V0 = 10.29m/s
I then solved part a by using V^2 = V0^2 + 2 *a*(x-x0)
0=(10.29)^2 +2(9.8)(x-0)
i solved this and ended up with 5.40m
I got both of these wrong on my practice test. I would greatly appreciate if someone could explain to me what i did wrong. Thanks so much!