- #1
Chiborino
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Homework Statement
A skateboarder starts up a 1.0-m-high, 30-degree ramp at a speed of 7.0 m/s. The skateboard wheels roll without friction. How far from the end of the ramp does the skateboarder touch down?
angle = 30 degrees
vi = 7.0 m/s
a = -9.8 m/s2
initial height = 1 m
Homework Equations
y = x*tanθ + ax2/(2*vi^2*cos2θ) [graphs the path of a projectile]
vf=vi+at
vf2=vi2+2ad
dy=viyt+.5at2
dx=vixt
The Attempt at a Solution
First, I graphed the path of the projectile, and since it forms a parabola whose roots are the max distances, I got an answer of 5.65 m. The homework problem is online, so it told me that it was wrong.
Not knowing where I went wrong graphing it, I found the time it spent in the air by plugging into vf2=vi2+2ad, and then plugging vf into vf=vi+at for t0 to the max height. Then I just used the diy= .5at2 equation to find the time form the peak to the ground. The total time I got was .933 seconds. Multiplying this by the horizontal component of his velocity (vi*cosθ = 7.0*cos30 = 6.1) I got 5.69 seconds (probably a little different from my calculator since my calculator ignores significant figures even more than I do). Again, this was wrong.
So I gave up and clicked show answer: 3.78 meters.
I don't get how my teacher got this answer.
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