Question

A marble rolling on a smooth floor has an initial velocity of 0.4/s If the floor offers a retardation of 0.02m/s² calculate the time it will take to come to rest.

Answer 1

u=0.4m/s
v=0
a=-0.02m/s
v=u+at
0=0.4+-0.02*t
t=0.4/0.02
t=20second

Answer 2

Retardation = -0.02 m/s²
u= 0.4m/s
v=0 (cuz finally it will come to rest)

We know that,
a=(v-u)/t
-0.02=0-0.4/t
-0.02=-0.4/t
-0.02t=-0.4
t= -0.4/0.02
t (time) = 20 sec


Hope it helps!
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