Short Answer 
Newton’s second law states that force is the product of mass and acceleration (F = ma), indicating that a lower mass leads to higher acceleration under the same force. In this example, the kickball accelerates more than the soccer ball when kicked with the same force, demonstrating that the kickball has less mass than the soccer ball.
Step 1: Understanding Newton’s Second Law
Newton’s second law states that force equals mass times acceleration (F = ma). This means that for a given force applied to an object, the object’s mass and acceleration are inversely related. When the same force is exerted, a lower mass will experience a higher acceleration.
Step 2: Analyzing the Forces on the Balls
When both the kickball and soccer ball are kicked with the same force, their respective masses will determine how much they accelerate. If we observe that the kickball accelerates more than the soccer ball, it implies that it must have a lower mass compared to the soccer ball. This observation aligns with the principles outlined in Newton’s law.
Step 3: Conclusion on Mass and Acceleration
The conclusion drawn from the above analysis is straightforward. Since the kickball accelerates more than the soccer ball under the same kicking force, it confirms that the kickball has less mass. Therefore, the relationship depicted by Newton’s second law has been demonstrated through this example of different balls being kicked.