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STOPPING DISTANCEOF A RACE CAR- During a test bythe editors of an auto magazine,

ID: 2836809 • Letter: S

Question

STOPPING DISTANCEOF A RACE CAR-

During a test bythe editors of an auto magazine, the stopping distance s (in ft) ofte MacPHerson X-2 racing car conformed rule

where t is time in seconds after brakesapplied

a) Find an expression for the car's velocity v at anytime t.

b) What was the car's velocity whn brakes were firstapplied?

c) What was the car's stopping distance for thatparticular test??

STOPPING DISTANCEOF A RACE CAR- During a test bythe editors of an auto magazine, the stopping distance s (in ft) ofte MacPHerson X-2 racing car conformed rule s = f(t) = 120t-15t^2 ( t > = 0) where t is time in seconds after brakesapplied a) Find an expression for the car's velocity v at anytime t. b) What was the car's velocity whn brakes were firstapplied? c) What was the car's stopping distance for thatparticular test??

Explanation / Answer

a> s(t) = 120t-15t2

     s'(t)= v(t)= 120 - 30t

b> v(0)= 120- 30*0=120ft/s

c> when the velocity will be zero the car will stop.

so v(t)=0 =>t=4s so s =120* 4 - 15* 16= 240ft