Spring constant, pendulums and and angular momentum all rolled into one

[heatherjones.]

there is a block on a slope (that is compressing a spring) and it is released and fired up the slope towards an inverted pendulum (that's leaning on the end of the slope) with just enough speed that the combination reaches (Theta)=0 degrees with no speed.

Find the Spring constant

the angle of the slope is 20 Degrees, the angle between the leaning pendulum and the vertical axis is also 20 degrees. the angle between the slope and the pendulum should be 90 degrees

there is no friction,
the rod of the pendulum is mass-less
the distance the spring is originally compressed is (delta)x=4.5cm
the block travels a distance of L=45cm
the rod of the pendulum is R=17cm in length
mass of the block is m2=.45 kg
mass of the bob at the end of pendulum is m1=.38kg

both the masses stick together

there was no more information given, and this was a spur of the moment question the teacher created in class.

i drew a picture too if that could help, http://imageshack.us/photo/my-images/42/physixprblem.png/

we didn't get to finish it in class and no one could figure out how to solve it yet.can anyone manage to figure out how it works? i showed my professor my work and still i don't understand where i went wrongi know energy of angular momentum is conserved and the collision does not conserve energy... but when i looked back over my notes i still don't even know where to begin again on this problem.

i think it involves the following formulas at the very least, but i never got any further! i know it requires more than this...

Kinetic(rotational)=(1/2)(Inertia)(omega)
Potential(bob)=mgh
L(angular momentum)=Inertia*(Omega)

 

[Drakkith]

I would post this in the Homework forums to ensure you get the best help possible, as per PF rules!