Speedy Sue, driving at 30.0 m/s, enters a one-lane tunnel. She then observes a slow-moving van?
155 m ahead traveling at 5.00 m/s. Sue applies her brakes but can accelerate only at 22.00 m/s2 because the road is wet. Will there be a collision? State how you decide. If yes, determine how far into the tunnel and at what time the collision occurs. If no, determine the distance of closest approach between Sue’s car and the van.
Please explain how you get the answers so that I can understand the problem. Thank you in advance
More Questions From This User See All
Answers & Comments
Such acceleration (-22 m/sec^2) stops a car proceeding at 108 km/h in 20 m ....that's not a wet brake but instead a superdry brake of a sports car .
If, instead, -2.2 m/sec are considered, then :
(0-ΔV^2) = 2*a*d
d = -25^2/-4.4 = 625/4.4 = 142 m > 155....collision won't take place
It is the same as if she was moving at 25 m/s, heading for a wall 155 m ahead. It takes her 14.20 m and t = 1.126 seconds to stop (relative to the van).
t = 25 / 22 = 1.136 seconds.
d = 25t - 0.5*22*t^2 = 14.20 meters