An object of mass M is subject to two constant forces: F1, pointing in the x-direction, and F2, pointing in the y-direction. Show that the motion is one of constant acceleration. Find the magnitude and direction of this uniform acceleration. (Use the following as necessary: M, F1 and F2 for the magnitudes of F1 and F2.)
if all the forces are constant, their sum will be constant.
F = ma
so if F is constant, a is constant (I think we can assume that M does not change...)
The resultant force F is just
F = F1+F2
use normal vector addition.