# Energy Conservation & Potential Energy.. Spring/Friction Problem

by Help1212
Tags: conservation, energy, potential, spring or friction
 P: 9 1. The problem statement, all variables and given/known data A 0.80-kg block is held in place against the spring by a 67-N horizontal external force. The external force is removed, and the block is projected with a velocity v1 = 1.2 m/s upon separation from the spring. The block descends a ramp and has a velocity v2 = 1.9 m/s at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction is 0.39. The velocity of the block is v3 = 1.4 m/s at C. The block moves on to D, where it stops. In Fig. 7.4, the force constant of the spring is.. 2. Relevant equations K1 +U1 +W other = K2+ U2.. ect .. U2=0.5kx^2 .. K1=(0.5)mv^2 3. The attempt at a solution I've tries solving the problem with the equation above but I really just don't know where to start especially since there are no units of distance given.. Can someone lead me in the right direction please?
 PF Patron HW Helper Sci Advisor Thanks P: 25,531 Hi Help1212! (try using the X2 and X2 icons just above the Reply box ) I assume you can find kx and kx2/2 ? ok, then k = … ?
 P: 9 euhh... i'm still a little confused..how do i find k if I don't know x?
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