(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A skier comes crashing into the netting at the bottom of a ski hill. The skier has a mass of 85 kg and is moving at a speed of 65 km/h (234 m/s).

(a) How much work is done by the netting while bringing the skier to rest?

(b) If the "spring" constant for the netting is 13500 N/m, how far is the netting stretched when the skier comes to rest?

m = 85 kg

v1 = 234 m/s

v2 = 0 m/s

k = 13500 N/m

w = ?

[PLAIN]http://upload.wikimedia.org/math/f/5/d/f5d889f32d6794e1bc2ed394e9688c76.pngx[/URL] [Broken] = ?

2. Relevant equations

(F)(d) = [1/2(m)(v2^2)] - [1/2(m)(v1^2)]

KE = [1/2(m)(v^2)]

PEe = [1/2(k)(x^2)]

3. The attempt at a solution

(a)

W = [PLAIN]http://upload.wikimedia.org/math/f/5/d/f5d889f32d6794e1bc2ed394e9688c76.pngKE[/URL] [Broken]

= [1/2(m)(v^2)]

= [1/2(85 kg)(234 m/s)^2]

= 2327130

= 2.3 x 10^6 J

This answer seems reasonable.

(b)

Now here is where I need help.

2.3 x 10^6 J = [1/2(k)(x^2)]

2.3 x 10^6 J = [1/2(13500 N/m)(x^2)]

x = sqrt{[-2.3 x 10^6 J]/[1/2(13500 N/m)]}

x = 18 m

Does this look right?

Thanks in advance!

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