 Physics Help Forum What does assuming a maximum deceleration mean in the following problem?
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 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum Jul 10th 2014, 09:07 PM #1 Junior Member   Join Date: Jun 2014 Posts: 22 What does assuming a maximum deceleration mean in the following problem? In a crash simulation, a car traveling at x m/s can stop at a distance d meters with a maximum deceleration. If the car is traveling at 2x m/s, which of the following statements are true, assuming a maximum deceleration? Thanks Physics Forum!   Jul 11th 2014, 04:37 AM #2 Physics Team   Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,352 I have no idea why they say it stops with "maximum deceleration." If the problem said the car stops with "constant decelaration" then you can use the standard time-distance formulas, such as v_2^2 - v_^2=2ad. But by using the phrase "maximum deceleration" it seems that they want you to consider the possibility that acceleration is not constant, but rather varies, and could in fact for a brief period of time be virtually unlimited. Perhaps if you post the rest of the problem it would be clearer what they're getting at.   Jul 11th 2014, 10:04 PM #3 Junior Member   Join Date: Jun 2014 Posts: 22 Hey ChipB, The rest of the problem went: choose the correct answers. The stopping time is doubled, the stopping distance is doubled, and the stopping distance is quadrupled. The answers were the stopping time is doubled and the distance is quadrupled. I was wondering if maximum deceleration had something to do with velocity final equaling zero? And from there I can set up my kinematics equation so that I can see the relationship in respect to proportion. Thanks ChipB!   Jul 12th 2014, 05:42 AM #4 Physics Team   Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,352 OK, what they mean is to assume that the deceleration is the same in both scenarios - i.e., 'a' is constant. So from v_2^2 -v_1^2 = 2ad, you can see that if v_i is doubled, and v_2 is zero, d is quadrupled. From v_2 = v_1 + at, if v_2 is doubled then t is doubled.  Tags assuming, deceleration, maximum, problem Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post helloworld10145 Kinematics and Dynamics 2 Sep 17th 2013 07:50 PM oswaldo Advanced Mechanics 3 Feb 7th 2011 02:20 PM yshridhar Kinematics and Dynamics 1 Aug 23rd 2010 04:04 AM mola Advanced Optics 1 May 24th 2009 09:34 PM s3a Kinematics and Dynamics 5 Apr 5th 2009 04:39 AM