This is a problem that i thought up, not a homework problem! There is an incline plane of Mass Ma, whose incline is at an angle theta with the horizontal. There is a block on this incline whose mass is Mb. There is no friction or gravity. There is a horizontal leftwards force applied on the inclined planeto push it to the left. The push would cause the small block to rise and accelerate. The inclined plane is either attached to a horizontal rail, or is a double sided incline plane and rests on a frictionless surface so to ignore the torque created by the inertia of the block around the right angle vertex of the incline. The force pushing the plane to the left is Fext. What is the acceleration of the block relative to an inertial reference frame. I tried to solve it, and when i thought i finally got the right answer it came out to be logically incorrect when i graphed it. Can anyone solve it and show the work? If you can't then check out the attachment. Thats what I tried. I don't see anything wrong with any of my logical steps, but the final result only looks normal on the graph when the mass of the small block is less than that of the inclined plane. But the ratio shouldn't affect the resulting graph shape.