The behavior of a moving ball can be influenced by various forces. When subjected to air drag and ground impact, its horizontal velocity decreases, causing it to fall behind a moving vehicle. Due to energy loss on impact, each subsequent bounce is lower than the previous one, indicating that such scenarios do not typically pose a threat to a vehicle’s windshield.
In a different scenario, if a rock is dropped from a window or falls from a truck carrying gravel, its movement is affected upon hitting the road. The frictional force between the rock and road surface decreases its horizontal velocity, which can increase the likelihood of an incident. Furthermore, the irregular shape of a rock could cause it to spin upon impact, possibly making it bounce higher than its initial drop due to the conversion of rotational energy into translational energy, a concept consistent with the conservation of energy laws.
An illustration of this situation involves a vehicle traveling at a high speed, such as 70 miles per hour, approaching a stationary rock at the apex of its trajectory. In this instance, the vehicle collides with the rock rather than the other way around, leading to a damaged windshield.
In the absence of a truck in front of a vehicle, rocks that have been dislodged by another vehicle’s tire often cause windshield damage. Contrary to popular belief, the rock is not propelled backward; rather, it begins at rest when lodged between the tire treads and makes contact with the ground. Such occurrences are more common and contribute to vehicle damage in scenarios where rocks lie on the road and are subsequently displaced by other vehicles.
