Question

A car is traveling at 54km/hr if its velocity increases to 72km/hr in 5 sec then find the acceleration of the car in SI units

Answer 1

To covert km/h to m/s multiply it by 5/18.
So,u=54k/h i.e 15m/s
V=72km/h i.e 20m/s
t=5sec
a=v-u÷t
i.e a=20-15÷5=1m/s^2

Answer 2

$\textbf{\underline{\underline{According\:to\:the\:Question}}}$

★As above the acceleration of car is to be described in SI units.

★As we know that the SI unit is distance is metre.

★SI unit of time is second. Hence we have to calculate the velocities in m/sec.

◆Therefore,

Initial velocity

u = 54 km/h

→Convert it into m/sec

$\tt{\rightarrow\dfrac{54\times 1km}{1h}}$

$\tt{\rightarrow\dfrac{54\times 1000m}{3600s}}$

$\tt{\rightarrow\dfrac{540}{36}}$

= 15 m/s

★Final velocity

v = 72 km/hr

→Convert it into m/sec

$\tt{\rightarrow\dfrac{72\times 1km}{1h}}$

$\tt{\rightarrow\dfrac{72\times 1000m}{3600s}}$

$\tt{\rightarrow\dfrac{720}{36}}$

= 20 m/sec

★Time taken = 5sec

$\tt{\rightarrow Acceleration=\dfrac{v-u}{t}}$

$\tt{\rightarrow Acceleration=\dfrac{20-15}{5}}$

= 1 m/s²

★Therefore

→Acceleration of car in SI unit is 1 m/s²