• # question_answer A car starting from rest acquires a velocity of 54 $km{{h}^{-1}}$in 20 seconds. What is its acceleration? A) $2.7m/{{s}^{2}}$   B)  $1.08m/{{s}^{2}}$ C) $1m/{{s}^{2}}$      D)  $0.75m/{{s}^{2}}$

Acceleration $\text{=}\frac{\text{change}\,\text{in}\,\text{velocity}}{\text{time}}$ $=\frac{54km/h-0}{20}=\frac{54m/s-0}{20}=0.75m/{{s}^{2}}$ $\left( \because 54\,km/h\frac{54\times 1000m}{3600\sec }=15m/s \right)$