Projectile Motion: Skateboarder on a Ramp

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Homework Help Overview

The discussion revolves around a projectile motion problem involving a skateboarder launching off a ramp. The skateboarder starts from a height of 1.0 m at an angle of 30 degrees with an initial speed of 7.9 m/s. Participants are exploring how to calculate the distance from the end of the ramp to where the skateboarder lands.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the initial conditions of the skateboarder's motion, including the angle of the ramp and the initial speed. There is confusion regarding whether the initial speed is at the top or bottom of the ramp, and the role of friction in the calculations is questioned. Some participants attempt to calculate the horizontal and vertical components of the velocity and the time of flight.

Discussion Status

The discussion is ongoing, with participants clarifying the initial conditions and questioning the assumptions made in their calculations. Some have attempted calculations but have received feedback indicating their results may be incorrect. There is a recognition of the need to clarify the height difference between the ramp and the landing point.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may impose specific rules or methods for solving the problem. The initial speed's reference point (top vs. bottom of the ramp) is a critical aspect under discussion.

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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?
-------------------
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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