Question

A car starts from rest is uniformly accelerated by 2 ms^-2, later on it retards uniformly by 4 ms^-2 and becomes at rest. It car remains moving for 3 s, then find out the maximum speed of the car.

Answer 1

u = 0, a₁ = 2 ms^-2

a₂ = -4 ms^-2

∵ v = u + at

∴ v = 0 + a₁t₁

⇒ t₁ = \(\frac{v}{a_1}\)

During retardation

0 = v - a₂t₂ ⇒ t₂ = \(\frac{v}{a_2}\)

∴ t₁ + t₂ = 3