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Deceleration (Posted on 2003-10-02) Difficulty: 3 of 5
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. 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/sec².
Bill never changes his speed.
Each car is 13 ft long and 7 ft wide.

Will there be a collision?

See The Solution Submitted by DJ    
Rating: 4.2308 (13 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: okay, here goes | Comment 4 of 16 |
(In reply to okay, here goes by FatBoy)

Sorry FatBoy. (But I am getting better, though: I didn't work on the problem until after it was posted live.)

The problem with your solution, though, is at time t=4.67 seconds, the acceleration given would have George's car already going backward into the intersection a second time, and that's the only reason it looks so close.

  Posted by Charlie on 2003-10-02 09:43:34

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