Brain Teaser?

Question

You can go to http://www.mindchallenger.com for brain teasers like this along with answers to some.

George is driving 100 ft/sec toward an intersection. He looks to his right, and sees Bill, driving 30 ft/sec toward the same intersection (they are approaching at right angle towards each other and not head on). George foolishly slams on his brakes. If he had kept going 100 ft/sec, he would have been through the intersection long before Bill got there. At the instant that he slams on his brakes, the center of George's car is 125 ft from the intersection, and the center of Bill's car is 150 ft from the intersection. George's brakes give his car an acceleration of -30 ft/sec/sec. Bill never changes his speed. Each car is 13 ft long and 7 ft wide. Is there a collision?

Interesting. Different equations giving different answers. Who is right and why?

Answer 1

no!
bill at his speed would reach the intersection in 5 seconds..
george would reach in 4.38 seconds.
but if george is decelerating at -30 ft/sec/sec his car should reach a stop in 3.33 seconds, giving the other guy plently of space to drive on by!

is that correct? i would feel like i genius if it was!

Answer 2

there is a collision
Bill will be at the intersection at t = 150/30 = 5 sec
George will be also at the intersection at t = 5 sec
. . . . S = 100(5) - 1/2(30)(5^2) = 125 ft
George is still in its final velocity of 50 fps
.

Answer 3

It will take Bill 5 seconds to reach the intersection.

In second 1, G averages 85 ft/sec, and has 40 ft left.

In second 2 he averages 55 ft/sec, so has passed the intersection.

NO COLLISION

Answer 4

I sure hope not, think of all the problems, it would cause, and I hope they had insurance!, then courts, man forget about the problem, did they or not?, hope they are ok.