Q: A car start from rest and moves with uniform acceleration of 5 m/s2 for 8 sec. if the acceleration ceases after 8 seconds then find the distance covered in 12 s starting from rest.

Sol. The velocity after 8 sec v = 0 + 5 × 8 = 40 m/s

Distance covered in 8 sec

S = 0 + (1/2) × 5 × 64 = 160 m

After 8s the body moves with uniform velocity and distance covered in next 4s with uniform velocity.

S = vt = 40 × 4 = 160 m

The distance covered in 12 s = 160 + 160 = 320 m.