- #1

spartan55

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## Homework Statement

A professional skier's initial acceleration on fresh snow is 90% of the acceleration expected on a frictionless, inclined plane, the loss being due to friction. Due to air resistance, his acceleration slowly decreases as he picks up speed. The speed record on a mountain in Oregon is 180 kilometers per hour at the bottom of a 29.0deg slope that drops 197 m. What exit speed could a skier reach in the absence of air resistance (in km/hr)? What percentage of this ideal speed is lost to air resistance?

## Homework Equations

We are only on kinematics....

(v_final)^2 = (v_initial)^2 + 2*(a_parallel)*(x_final - x_initial) , where a_parallel = g*sin(29)

## The Attempt at a Solution

I used trig to solve for the length of the ramp:

l*sin29 = 197

l = 406.35 m

Then I plugged this into the above kinematics equation and solved for v_final:

(v_final)^2 = 0 + 2*g*sin(29)*(406.35 - 0)

v_final = 62.14 m/s

I converted this to km/hr:

62.14 m/1s * 1km/1000m * 3600s/1hr = 223.7 km/hr, but this isn't the correct answer. I'm not sure where I went wrong.