Question

The velocity of car change from 18Kmph to 72kmph in 30s.what will be it's acceleration in kmph*2 and in m/s*2

Answer 1

For calculating acceleration in kmph², time should be in hour.


Given time = 30s

We know that 1 s = 1/3600 hr

=> 30 s = 30/3600 hr

=> 30s = 1/120 hr

Now Acceleration =
$\frac{v - u}{t}$


Here v = 72
u = 18

and t = 1/120

=> Acceleration =
$\frac{72 - 18}{ \frac{1}{120} } \\ \\ = >( 72 - 18) \div \frac{1}{120} \\ \\ = > 54 \times 120 \\ \\ = 6480$


So acceleration = 6480 km/h²

Now for m/s


18 kmph = 18 × 5/18 m/s

= 5 m/s

Similarly, 72 kmph = 20 m/s


So acceleration =
$\frac{20 - 5}{30} = \frac{15}{30} \\ \\ = \frac{1}{2}$


1/2 m/s²