if stopping distance increases in the rain, then why is increased road friction a contributing factor to worse fuel economy in the rain?
In: Physics
More stuff on the road (like rain, snow, etc.) makes it harder for the car to slow down and stop. It requires more effort for the car to work through whatever is on the road in order to be able to push down onto the actual surface and stop. Requires more energy = worse fuel economy
It isn’t. Road friction decreases in the rain. That could make fuel economy slightly worse as the tires might slip slightly, and fuel economy also decreases because the car has to move water out of the way as you move forward. This is a pretty negligible impact though.
There’s a difference between rolling friction and grip friction. Rolling friction is how much resistance there is to a wheel that is rolling, and it goes up in the rain as the wheel needs to move the water out of the way to roll. Grip friction is the friction between the tire and the ground.
It’s not friction that increases when the road is wet, it’s rolling resistance. It’s harder for the tire to roll through the road because it must displace water.
Water’s heavy, but it doesn’t help hold a tire to the ground. It’s gotta be moved outta the way by the tire, but some of it stays between the tire and the ground making it slippery.
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