Question

calculate the initial velocity of a train which is brought to rest by braking in 2 minutes,if the retardation is 0.2 m/s*²​

Answer 1

Answer :

Time interval = 2 minutes

Acceleration of train = -0.2 m/s²

(Negative sign shows retardation)

Final velocity = zero (i.e., rest)

$\star$ Since acceleration is said to be constant throughout the motion, we can easily apply equation of kinematics to solve this question.

Time taken by moving object to come at rest is called stopping time.

First equation of kinematics :

• v = u + at

v denotes final velocity

u denotes initial velocity

a denotes acceleration

t denotes time

★ Conversion :

⭆ 1 min = 60 s

⭆ 2 min = 2 × 60 = 120 s

By substituting the values, we get

➙ v = u + at

➙ 0 = u + (-0.2)(120)

➙ u = 24 m/s