Final answer:
Increasing the inclination angle of a plane will increase the acceleration of an object sliding down due to a greater component of gravity acting down the slope, while the normal force actually decreases as the angle increases.
Step-by-step explanation:
Increasing the angle of inclination on an inclined plane will increase the acceleration of an object sliding down the plane, assuming the coefficient of friction remains constant. This happens because as the incline angle increases, the component of the gravitational force acting down the slope (mg sinθ) increases, leading to a greater net force on the object and thus a greater acceleration.
The normal force, which is perpendicular to the surface of the incline, will not increase. In fact, the normal force decreases with an increased incline because the normal force equals mg cosθ, where θ is the angle of the incline, and as θ increases, cosθ decreases.
Thus, the correct answer to the question is: a) Increase the acceleration.