Q. The distance travelled by a motor car in $t$ seconds after the brakes are applied is $s$ feet, where $s = 22t - 12t^{2}.$ The distance travelled by the car before it stops, is
A) 10.08 ft
B) 10 ft
C) 11 ft
D) 11.5 ft
Explanation
(a)
Given , $s = 22t - 12t^{2}$
$\therefore\ \ v = \frac{ds}{dt} = 22 - 24t$
When the car stop, $v = 0,22 - 24t = 0$
$\Rightarrow t = \frac{11}{12}$
$\therefore\ \ s = 22\left( \frac{11}{12} \right) - 12\left( \frac{11}{12} \right)^{2} = 10.08\ ft$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.