Maximum speed on a flat curve
A car rounds a flat curve of radius 40 m. The coefficient of static friction between tires and road is 0.5, and g = 10 m/s². What is the maximum speed before the car skids?
Answer B: explanation for every choice
A
This halves the correct result.
B
Correct. Friction supplies the centripetal force: μmg = mv²/r, so v = √(μgr) = √(0.5 × 10 × 40) = √200 ≈ 14 m/s.
C
This is √(gr), which ignores the friction coefficient.
D
200 is v², before taking the square root.
TakeawayFlat curve: vmax = √(μgr), independent of mass.
Equations usedCentripetal acceleration and forceFriction
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