Question

A car is traveling up a 1.5% grade at 65 mi/hr on good, wet pavement. The driver brakes to try to avoid hitting a cone on the road that is 300 ft ahead. The driver’s reaction time is 1.5 second. When the driver first applies the brakes, a software flaw causes the braking efficiency to lower to 0.8 for 100 ft. After the initial 100 ft, the braking efficiency returns to 1.0. How fast will the driver be going when the cone on the road is hit if the coefficient of rolling resistance is constant at 0.015? (Assume minimum theoretical stopping distance and ignore aerodynamic resistance.)

Answer 1