Projectile Motion: Skateboarder on a Ramp

AI Thread Summary
A skateboarder launches from a 1.0-meter high ramp inclined at 30 degrees with an initial speed of 7.9 m/s. The skateboard wheels are frictionless, which simplifies the calculations. The skateboarder’s horizontal and vertical velocities are calculated as 6.84 m/s and 3.95 m/s, respectively. The main confusion arises from the height difference between the ramp's end and the ground, affecting the projectile motion calculations. Ultimately, the skateboarder touches down at a distance of 1.8 meters from the base of the ramp.
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Homework Statement


A skateboarder starts up a 1.0--high, 30 ramp at a speed of 7.9 . The skateboard wheels roll without friction. How far from the end of the ramp does the skateboarder touch down?


Homework Equations



x=x0+v0t+.5(a)(t2)
v=v0+at

The Attempt at a Solution


This question seems pretty straight forward and I've found an answer but the website we use says it's wrong. First I found vx=7.9cos(30)=6.84 and vy=7.9sin(30)=3.95. I tried finding maximum y by solving vy=0=-9.8*t1 then t1=.405 and plugging that into y=1.8 then finding t2 when y=0 and y0=1.8 to get t2=.605 so ttotal=1.01 and plugging that into x=6.913
 
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A skateboarder starts up a 1.0--high, 30 ramp at a speed of 7.9 . The skateboard wheels roll without friction. How far from the end of the ramp does the skateboarder touch down?
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My understanding that it starts off a flat ramp top.
I do not understand whether the friction has any factor in the calculation.
With zero initial vertical velocity, in my calculation the distance from the base is 1.8m
 
sorry 30 ramp is supposed to be 30o ramp
 
What immediately occurs to me is that the ground (where the skateboarder touches down) is at a different height to the end of the ramp (where ballistic motion starts).
The 7.9m/s is at the bottom of the ramp, not the top.
 
Yeah that was it the 7.9 was at the bottom of the ramp not the end of the ramp thanks
 
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Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
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