Question

Physics

Answer 1

Instead of my question, I posted the word physics!

Answer 2

A train moves with a uniform velocity of 24 meter/ seconds. The driver applies brakes and the train comes to rest with a uniform retardation in 12 seconds. What's the retardation, velocity of train after 4 seconds, and distance covered by train after the brakes are applied

Answer 3

so it's asking three separate things:
1. the retardation (I'm going to use the word deceleration instead) of the train
2. the velocity after 4 seconds
3. the distance covered by the train after the brakes are applied

off the bat, you are only given the initial velocity (24 m/s) and the time to brake (12 seconds). the first thing they ask for is the deceleration of the train.

you can use the kinematics equation

vf = v0 + at

where vf is the final velocity (0, since it's coming to a stop)
v0 is the initial velocity (24 m/s)
and t is time (12 seconds)
plug in and solve for a (the deceleration)

Answer 4

now, for the velocity after 4 seconds, you can simply re-use the same equation

vf = v0 + at
this time, you'll plug in the v0 (still 24 m/s), the deceleration from the previous part, and t = 4 seconds

Answer 5

last part: the distance covered by the train after the brakes are applied

d = v0 * t + (1/2)at^2

where d is the distance (which you'll solve for)
v0 is initial velocity (still 24 m/s)
t is time (still 12 seconds)
a is the deceleration (which you have from part 1)
plug in and solve for d