Question

an object moving north with an initial velocity of 60 m/s brought to rest after a distance of 120 m. assume acceleration is uniform calculate retardation and time interval

Answer 1

Answer:

let the distance be , s, 120m

acceleration be, a

final velocity be, v, i.e 0 m/s

initial velocity be , u ,i.e 60m/s

from the third equation of motion,

2as=v^2 -u^2

2a * 120 = 0^2 -60^2

2a = -3600/120

2a= -30

a =-15

therefore, acceleration = -15m/s^2

now from the first equation of motion,

a=(v-u)/t

-15= (0 - 60)/t

-15t= -60

t=-60/-15

t = 4

therefore time interval is 4 seconds