Simplification Problem



Hi everybody,

I'm new to this list and I hope it will help me to become aquainted with 
Maxima. Maxima is doing some job so astonishing well and then appears to 
become complete dumb. (Probably, I am the dummy...)

I am solving a differential equation describing the motion of an object 
on an laterally inclined plane. The object is subject to Coulomb 
friction an moves initially in longitudinal direction. This is may 
Maxima code:

/* Definitions and ranges */
logexpand:all;
assume(a>0,v0>0);
v:v0-a*t;
/*   This is for Output in TeX */
texput(alpha,"\\alpha");
texput(v0,"v_0");
/*
   Solving of the differential equation with initial conditions
   y(0) = 0
   v(0) = v_0
  */
'diff(y,t,2)+a*'diff(y,t)/v-g*sin(alpha)=0;
ode2(%,y,t);
ic2(%,t=0,y=0,'diff(y,t)=0);
/* Simplification of the solution */
%*4*a^2/(sin(alpha)*g);
fullratsimp(%);
radcan(%);
tex(%);	

There are obviously possible simplifications for the Maxima output, 
applying Binomic formulas and applying
log(a) - log(b) = log(a/b)

but I cannot convince Maxima to apply this simple rules :-(

This is a general problem for me when working with Maxima: I seldomly 
succed in compacting the output.

Any ideas? BTW: Is there any tutorial demonstrating the approach to real 
world problems (like above) with Maxima?

Greetings from M?nster, Germany
Wolfgang Hugemann