Question

A car travelling at 20km/h, it speeds up to 60km/h in 6 seconds. What is its acceleration?

Answer 1

u= 20 km/h = 20*5/18= 50/9 m/s
v= 60 km/h = 60*5/18= 50/3 m/s
t= 6 s
a= v-u/t
  = 50/3-50/9÷6 
  = 100/9÷6
  = 100/9×1/6
  =  50/27 m/s^2

Answer 2

The car acceleration is $1.85\ \mathrm{m} / \mathrm{s}^{2}$.

Given data:  

Initial velocity of a car is 20 km/h  

The speed is up to 60 km/h in 6 seconds.  

Initial velocity u = 20 km/h  

Final velocity v = 60 km/h  

Time t = 6 seconds.  

$u = 20\ km/h = \frac{50}{9}\ m / s$

$v = 60\ km/h = \frac{50}{3}\ m / s$

Acceleration, $a=\frac{v-u}{t}$

$\begin{aligned} a &=\frac{\left(\frac{50}{3}-\frac{50}{9}\right)}{6} \\ a &=\frac{\left(\frac{100}{9}\right)}{6} \\ a &=\frac{50}{27}=1.85\ \mathrm{m} / \mathrm{s}^{2} \end{aligned}$