Question

A car starts from rest and moves along the x-axis with constant acceleration 5 ms^–2 for 8 seconds. If it then continues with constant velocity, what distance will the car cover in 12 seconds since it started from the rest?

Answer 1

For constant acceleration of car,

u = 0, a = 5 ms⁻², t = 8 s

using s = `"ut" + 1/2 "at"^2`, we get

s1 = `0 + 1/2 xx 5 xx 8^2`

= 160 m

For constant velocity of car,

v = u + at 

= 0 + 5 × 8

= 40 ms⁻¹

t = (12 − 8) s = 4 s, a = 0

∴ s₂ = vt 

= 40 × 4 

= 160 m

There fore, total distance covered in 12 s

= s₁ + s₂ 

= 160 + 160 

= 320 m