Planes and cars have problems braking if brakes are too hot. F1 teams complain also if brakes are too cold. What’s the reason behind so much variance?
Also, I have noticed, that basically any vehicle have smaller deceleration when moving fast than when moving slow. From elementary school physics – when I apply some force onto surface, I should get some amount of friction, so I don’t know why it changes. It this also related to the temperature, or is there unrelated mechanism behind it?
In: Physics
Elementary physics is idealized. It typically assumes that the coefficient of friction is constant. In real life, the friction coefficient will change depending on temperature.
The brakes are designed to operate within a certain safe temperature window and typical driving. For cars (not sure about planes), the brakes are NOT designed for repeated high braking operations done frequently. Doing this overheats the brake pads (boils the brake fluid too) etc and causes the brakes to fail or degrade.
F1 cars, on the other hand, are designed to have repeated braking. The compounds used are most effective when the brakes are hot (much hotter than road cars) but conversely they operate poorly when below a certain temperature.
You are almost certainly incorrect. Braking will cause more deceleration from a high speed compared to low speed. This is because the air resistance/drag at high speeds is much greater and this contributes to the car slowing down. But most drivers are conditioned or trained NOT to stamp on the brakes at high speeds because it results in the car sliding. So while it probably “feels” as though brakes work less effectively at high speed – that is related to the driver and not the physics.
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