A multistep/multiconceptual spring force challenge

[Rayquesto]

Homework Statement

A massless spring of constant k=78.4 N/m is fixed on the left side of a level track. A block of mass m=0.50-kg is pressed against the spring and compresses it a distance d from equalibrium position B to a compressed position A. The block, initially at rest, is then released and travels toward a circular loop of radius R=1.5m. The entire track and loop are frictionless excpet for the section of the track between ponts A and B. Given that the coefficient of kinetic friction between the block and the track along A and B is u of k is .30 and that the length of AB is 2.5 meters determine the minimum compression, d, of the spring that enables the block to just make it through the loop at point C. (Hint: the force of the track on the loop will be zero if the block barely makes it through the loop (max potential energy)).

Homework Equations

-kx=spring force
1/2*k*x^2=elastic potential energy
Kinetic Friction Force/Normal Force=coefficient of kinetic friction

The Attempt at a Solution

-(78.4N/m)(d)=(Fk)(2.5m)
Fk/Fn=uk; Fk/Fn=.3; Fn=(9.81m/s^2)(.5kg); Fk=-(.3)(9.81m/s^2)(.5kg)= -1.4715N

-kx=-1.4715N; -(78.4N/m)(d)=-1.4715; d=4.68centimeters compressed to move to the loop with the high spring constant given. Is this right, or is there something more to it? I kind of just ignored the circle part because it seems unneccessary.

 

[typhowowl]

Look at your first equation. The units are horribly wrong. Newtons is not equal to joules. Also, YOU NEED THE CIRCLE PART. You should have: spring potential energy=... type what you think should be next. I'll verify it asap.