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Old Nov 19th 2018, 12:42 PM   #1
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Question A little confused

Hey, I am on an access to higher education course in the UK and have come across the following problem in my workbook:

A car of weight 10780N driving at constant speed along a flat quiet road has resistive forces (friction drag etc.) of 350N acting on it, suddenly the car develops a misfire and its output drops so it now exerts a driving force of 190N. What will happen (initially) to the car? (calculation needed)

I know the car will decelerate initially as the output will be overcome by the resistive forces, but I am struggling with how to show this with a calculation.. I feel like its something very simple I'm missing but have been going round in circles for a while so any help appreciated. I'm quite new to studying physics so go easy on me please
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Old Nov 20th 2018, 01:41 AM   #2
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So , at constant speed resistance is 350N , the push from engine drops to 190N ... the shortfall is 160N

So there is a 160N deceleration force acting

The car has a mass 10780/9.81 = 1099Kg

F=ma .......... a = 160/1099 = 0.146 m/sec/sec
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Old Nov 20th 2018, 06:25 AM   #3
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Ah thatís perfect.. I wasnít seeing the deceleration as a force in its own right at 160 N .. many thanks!
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Old Dec 22nd 2018, 01:12 PM   #4
Pmb
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Originally Posted by oz93666 View Post
So , at constant speed resistance is 350N , the push from engine drops to 190N ... the shortfall is 160N

So there is a 160N deceleration force acting

The car has a mass 10780/9.81 = 1099Kg

F=ma .......... a = 160/1099 = 0.146 m/sec/sec
oz = you're supposed to help people. not do there homework for them. doing so violates the forum rules.
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Old Dec 22nd 2018, 10:01 PM   #5
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Originally Posted by Pmb View Post
oz = you're supposed to help people. not do there homework for them. doing so violates the forum rules.
OK ... I'll regulate my responses in future ... not spell it out so completely..
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