The acceleration experienced by an object will be proportional to the applied force and inversely proportional to its mass. If there are multiple forces, they can be added as vectors and it is the net force that matters.
Elevator problems and how acceleration affects the normal force are explained in this video with an example.
Use F=ma to solve for and know the relationships between force, mass, and acceleration, know that w=mg is a version of Newton's Second Law.
A list of student-submitted discussion questions for Newton's Second Law.
This study guide looks at Newton's three laws, free body diagrams, and types of forces, including the force of gravity, normal force, and friction force.