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Q & A: cruise control in wet weather

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Most recent answer: 06/15/2015
Q:
Dear physics expert,What are the physic principles or reasons that cruise control can't be used in wet weather? How does the traction change and how does the change in traction affect the cruise control?car manuals say you can't use it but I can't find an explanation based on ohysics as to exactly what happens.Thanks in advance for your time.
- Robyn Rutherford (age 41)
Gold Coast, QLD, Australia
A:

Cruise control senses the speed of the car and then adjusts the gas flow to the engine or the braking to reach a set speedand maintain it. In wet weather, that can be a bad idea. Traction is poor on wet spots, so if you're approaching a wetter part of the road you should slow down because braking is difficult there. Cruise control systems don't make that adjustment. Or maybe you see a big deep puddle ahead of you. Just going through it at full speed might be a bad idea. So you turn off the cruise control as a way to remind yourself that you'll be constantly making adjustments.

Mike W.


(published on 06/15/2015)

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