Final answer:
Hydroplaning can begin at speeds as low as 35 mph (56 km/h) and depends on conditions such as tire tread and road wetness. On wet surfaces, stopping distances increase due to lower friction, which is important to consider alongside driver reaction time.
Step-by-step explanation:
Hydroplaning on Slippery Roads
Hydroplaning, where tires lose contact with the road and ride on a layer of water, is a concern in heavy rain conditions. The condition creates a risk of losing control of the vehicle. While the exact speed at which hydroplaning can occur varies based on numerous factors such as tire tread depth and vehicle weight, it typically starts at speeds as low as 35 miles per hour (mph) or about 56 kilometers per hour (km/h). When a surface gets wet, especially with only a light rain, oil and gasoline can rise to the surface, increasing the risk of hydroplaning. In heavy rain, the increased water depth can potentially wash away the oil, but it also leads to deeper water on the road, which can enhance the risk of hydroplaning.
When considering the stopping distance of a vehicle, wet conditions significantly affect the braking performance. For example, a car traveling at 30.0 m/s (about 110 km/h) can decelerate at a rate of 7.00 m/s² on dry concrete, but this deceleration rate drops to 5.00 m/s² on wet concrete. Reaction time is a crucial factor in determining the total stopping distance, and on slippery roads, the stopping distances are lengthened due to decreased friction between the tires and the road surface.