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To stop a car, first u require a certain reaction time to begin braking;Then the car slows under constant braking deceleration. Suppose the total distance travelled by ur car during these two phases is 56.7m, when its initial speed is 80.5 kmph and 24.4m when its initial speed is 48.3kmph, 1)What is ur reaction time and 2)What is magnitude of deceleration?

To stop a car, first u require a certain reaction time to begin braking;Then the car slows under constant braking deceleration. Suppose the total distance travelled by ur car during these two phases is 56.7m, when its initial speed is 80.5 kmph and 24.4m when its initial speed is 48.3kmph,


1)What is ur reaction time and


2)What is magnitude of deceleration?

Grade:12

1 Answers

Badiuddin askIITians.ismu Expert
148 Points
12 years ago

Dear Chilukuri

let reaction time is t' and braking decelaration =a

in responce time car will move with constant velosity.

so

 56.7 = 80.5*5/18  *t'  + (80.5*5/18 )2/2a

56.7    =22.36 t'   + 250/a........................1

similerly

24.4  =48.3*5/18  *t'  + (48.3*5/18 )2/2a

24.4  =13.42 t'   + 90/a   ......................2

solve equation 1 and second  that wil be your answer

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