Question

a body is moving with the initial velocity of 20m/s on rough surface. the velocity of the body decrease at the rate of 0.4m/s². due to friction. After how much time will the body stop

Answer 1

u = 20m/s
v = 0 m/s
a -0.4 m/s^2
t = ?
a = (v - u ) / t
=> t = (v - u ) / a
=> t = ( 0 - 20 ) / - 0.5
=> t = -20 / -0.5
=> t = 40

Hence, after 40 seconds, the body will stop.

Mark it brainlist if helpful.

Answer 2

HI HERE IS YOUR ANSWER.
===============================
GIVEN

u =20 m/s

v=0 m/s

a= -0.4 m/s^2 (we take -ve because rate of acceleration decreases)

t= ?
SO,WE USE FIRST EQUATION OF MOTION.
v = u +at
at =v - u
t= v - u/a
PUT THE VALUE.

t = 0 - 20/-0.4
t= -20/-0.4
t= 50 s.
The body will stop after 50 s.
===============================
HOPE IT IS HELPFUL.