function F = F_slope(alpha, m)
%   F_SLOPE Angle of surface, mass
%   F_SLOPE(ALPHA, M) computes the horizontal component of
%   the force required to move a vehicle with mass M in
%   kilograms (including its rider) up an inclined surface
%   at angle alpha in degrees.

error(nargchk(2, 2, nargin));

g = 9.81;

t = m * g * sin((pi * alpha) / 180);

if (t < 0)
  F = 0;
else
  F = t;
end