When a block of mass m is placed on an inclined plane with an angle of inclination theta, three forces act on it: the force of gravity, the normal reaction force, and the force of friction. The normal reaction force (N) is the force exerted by the plane perpendicular to the block, the force of friction (f) is the force that opposes the motion of the block, and the net force (F) is the force that causes the block to move. In this answer, we will discuss the graphical representation of these forces as they vary with the angle of inclination.


As the angle of inclination of the plane increases, the normal reaction force (N) decreases. This is because the component of the force of gravity acting perpendicular to the plane increases with the angle of inclination, and hence the normal reaction force decreases. The graph between theta and N is a decreasing straight line.


The force of friction (f) is directly proportional to the normal reaction force (N) and the coefficient of friction (μ). As the angle of inclination increases, the normal reaction force decreases, and hence the force of friction also decreases. The graph between theta and f is a decreasing curve.


The net force (F) acting on the block is the difference between the force of gravity and the force of friction. As the angle of inclination increases, the component of the force of gravity acting parallel to the plane increases, and hence the net force also increases. The graph between theta and F is an increasing curve.


In conclusion, the normal reaction force (N) decreases, the force of friction (f) decreases, and the net force (F) increases as the angle of inclination of the plane increases. The graphical representation of these forces with respect to the angle of inclination is a decreasing straight line, a decreasing curve, and an increasing curve, respectively.