A car accelerates uniformly from rest on a straight horizontal road at 3 m/s ^2 for 4 s . The engine is then turned off, and the car coasts forward at the constant velocity it just acquired for a distance of 144 m . The total time of the car's motion is

Step-by-step solution

Initial velocity of the car, u = 0 Acceleration, a = 3 m/s ^2 Time spent accelerating, t₁ = 4 s Velocity acquired at the end of the acceleration phase is given by v = u + at₁ v = 0 + 3 4 = 12 m/s The car then coasts at this constant velocity for a distance d₂ = 144 m . Time taken for the constant velocity phase, t₂ = d₂ v = 144 12 = 12 s Total time of motion t_ total = t₁ + t₂ = 4 + 12 = 16 s Answer: 16 s