The purpose of using a helmet is to absorb and distribute the impact energy, reducing the risk of head injury. The experiment with the play dough balls helps Sam visualize how the force of an impact can vary with different speeds.
Additionally, by involving her dad, who has a larger head, and using a heavier ball in the second part of the experiment, Sam is exploring how factors like head size and mass might affect the results. Helmets are designed to fit securely on the head and provide protection regardless of the individual's head size.
This hands-on approach to understanding the physics of impact can be an effective way for Sam to grasp the concept of helmet safety and why it's crucial to wear one while riding a bike. It's a great example of applying scientific curiosity to real-life situations.