Question

A car increases its speed from 20 km/h to 56 km/h in 10 seconds. Its acceleration is equal to :

• A. $30{ms}^{-2}$
• B. $3{ms}^{-2}$
• C. $18{ms}^{-2}$
• D. $1{ms}^{-2}$

Answer 1

The correct option is D $1{ms}^{-2}$

Initial speed of the car $u=20km/h=20\times \frac{5}{18}=5.6m/s$
Final speed of the car $v=56km/h=56\times \frac{5}{18}=15.6m/s$
Time taken $t=10s$
Acceleration $a=\frac{v-u}{t}=\frac{15.6-5.6}{10}=1m/s^2$