Solution 4 on Equations of uniformly accelerated motion in 1D
Answer=B
- Initial velocity (u) = 108 km/h = 30 m/s.
- Final velocity (v) = 72 km/h = 20 m/s
- Time taken (t) = 5 seconds
Acceleration is calculated as
$\overrightarrow{a}=\frac{V_{f}-V_{i}}{t}$
a = (20-30)/5
a = -10/5 = -2 m/s2
Thus, the retardation of the car is -2 m/s2.