Question

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

Answer 1

u = 20 km/h = 20 * 1000/3600 = 5.55 m/s
v = 60 km/h = 60 * 1000/3600 = 16.66 m/s
t = 6 s
Therefore, acceleration = (v-u)/t = (16.66 - 5.55) / 6 = 1.851 m/s^2

Answer 2

u = 20 km/h = 20 * 5/18 = 50/9 m/s
v = 60 km/h = 60* 5/18 = 150/9 m/s
t = 6s
a = v-u / t = (150/9 - 50/9) / 6
  = 50/27 m/s^2  = 1.85 m/s ^2