Quick addition.
Re race cars- because of their wings and ‘ground effect’ (the suction holdig them to the track*). They get ‘pushed’ onto the track at more than their mass. They may have a mass of 1 ton but push down with 3 tons. Also racing tyres are very soft so can get a mu of more than 1. (We also know they’re expensive and wear out quickly).
The result a lot of push down plus sticky tyres means we get more than 1g acceleration from F1 cars. The racing harnesses etc show this. Also racing harnesses need to hold a driver in a crash, where there will be acceleration of much more than 1g. In a crash the acceleration is due not to friction, but to hitting an object.
*I’m sure you’re familiar with the Venturi effect from carburettors.
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