Answer Happy

1. A new fancy driverless car is traveling downhill during a test run and slams on the brakes. The mobile robot, which will eventually take over the world, skids 40 m before hitting a parked car with no remorse whatsoever. You have been hired as a physics expert to help the insurance investigators decide if the monstrosity had been traveling faster than the 25 MPH speed limit at the start of this event. The slope of the hill is 5º. Assuming braking friction has the usual form UN, what is the “critical value” of u for which you would conclude the car was speeding? Can you convince the investigators this killing machine was speeding, or do you need more information? While there are multiple ways to solve this problem, please solve it using work and energy