Problem 1: A car driving from Tucson to Nogales is distracted by some physics st
ID: 2001642 • Letter: P
Question
Problem 1:
A car driving from Tucson to Nogales is distracted by some physics students launching model rockets in the desert, veers off the road, and crashes into a cactus. The driver is luckily wearing his seatbelt, which causes him to decelerate from 110 km/hour to a dead stop in 50 milliseconds.
1. What is the average acceleration felt by the driver over this period?
2. How many times greater is this than the acceleration due to Earth’s gravity?
3. A driver not wearing a seatbelt would fly forward and strike the steering wheel, decelerating much more suddenly –- over, say, 6 ms. What is the acceleration (in "g’s", or multiples of Earth’s gravity) of the driver now?
Explanation / Answer
The velocity v = 110km/h * 1m/s / 3.6km/h = 30.6 m/s
1. The average acceleration is felt by the driver over the period a = v / t = 30.6m/s / 0.050s = 611 m/s² 62 "g"s
2. With no seatbelt,
3. The acceleration of the driver is a = 30.6m/s / 0.006s = 5093 m/s² 520 "g"s