On a rainy day the maximum frictional force between a car's tires and a certain level road surface is reduced to half its usual value. The maximum safe speed for rounding a curve is
A) unchanged.
B) reduced to 25% of its usual value.
C) reduced to 50% of its usual value.
D) reduced to 71% of its usual value.

Question

Quizplus · Accepted Answer

The maximum safe speed for rounding a curve is proportional to the square root of the frictional force. If the frictional force is reduced to half, the maximum safe speed is reduced to the square root of 1/2, which is approximately 0.71 or 71% of its usual value.

On a Rainy Day the Maximum Frictional Force Between a Car's