Question

A train is brought to rest within 20 seconds by applying brakes.Find the initial velocity if the retardation due to brakes is 2m/s²​

Answer 1

Answer:

Initial Velocity = $-40m/s^2$

Explanation:

Retardation (a) = $2m/s^2$

Final Velocity (v) = $0m/s^2$

Initial Velocity (u) = u

Time taken to come to rest(t) = 20secs

$acceleration = \frac{final velocity(v) - initial velovity(u)}{Time Taken(t)}$

$a = \frac{v-u}{t}$

$2 = \frac{0-u}{20}$

$40 = 0-u$

$40-0 = -u$

$u = -40m/s^2$

Therefore, the initial velocity of the train is $-40m/s^2$