Question

the speed of car is reduced from 144 km/hr hour to 72km/hr in 5 second . what distance traveled by car during this time interval​

Answer 1

$\huge{\underline{\underline{.........Answer.........}}}$

$\huge{\underline{Given:-}}$

Speed decreases from 144 km/hrs to 72 km/hr in 5 seconds.

$\huge{\underline{Explanation:-}}$

Firstly convert km/h in to m/s.

${\therefore 144 km/hr = 144 \times 5 /18 = 40 m/s}$

${\therefore 72 km/hr = 72 \times 5 /18 = 20 m/s}$

Now, finding its acceleration

$\huge{\boxed{\boxed{a = \frac{v - u}{t}}}}$

Substituting the values.

${a = \frac{20 - 40}{5}}$

${a = \frac{- 20}{5}}$

${a = - 4 m/s^2}$

$\huge{\boxed{\boxed{a = - 4 m/s^2}}}$

_________________________________________

Now,applying second kinematic equation

$\huge{\boxed{\boxed{S = ut + \frac{1}{2} a {t}^{2}}}}$

Substituting the values

${S = 40 \times 5 + \frac{1}{2} \times -4 \times {5}^{2}}$

${S = 200 - 50 }$

${S = 150 meters}$

$\huge{\boxed{\boxed{S = 150 metres}}}$

So, distance travelled by the car in this interval is 150 meters.