Newton's Laws - Mission NL7 Detailed Help

Force diagrams depicting the magnitudes and directions of the forces acting upon four objects are shown below. Each object has the same mass - approximately 5 kg. Rank these objects in order of their acceleration, from smallest to largest.

Newton's Second Law
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

The relationship between net force (Fnet), mass (m) and acceleration (a) is expressed by the equation
a = Fnet/ m

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The acceleration of an object depends directly on net force and inversely on mass. All four objects in the diagrams have identical mass. Thus, the net force will be the variable of importance in comparing the accelerations of the four objects.
Since acceleration is directly proportional to the amount of net force, the object with the smallest net force has the smallest acceleration. Inspect each diagram carefully to determine the amount of net force (vector sum of all the forces). Then in comparing the net force of each object, do not worry about the direction - left or right. Rank the four objects in increasing order of net force - which will be the same as the increasing order of their acceleration.