Question

a car travelling with a speed 126kmph a long a straight line comes to rest after travelling a distance 245m .the time taken by the car to come to rest, in second it

Answer 1

initial speed of the car is

$v_i = 126 km/h = 35 m/s$

finally car will stop after it covered d = 245 m

$v_f =  0$

$d = 245 m$

now by kinematics

$d = \frac{v_i + v_f}{2}*t$

$245 = \frac{35 + 0}{2}* t$

t = 14 s

so it will take 14 s to stop

Answer 2

Given is the data of the speed and the distance travelled by car, and we need to find out the time taken to travel the given distance with the given speed. Therefore, we will apply the equation of motion.

Given is the $u=126\frac { km }{ h },$ convert it into m/s which will be $35\frac { m }{ s }$.

Given that d = 245m. $d=(u+\frac { v }{ 2 } )\times t$.

$\Rightarrow 245=(\frac { [35+0] }{ 2 } )\times t$.

$\Rightarrow t = 14 seconds$.