Question

a speeding car changes its velocity from 108km/h to 36km/h in 4 sec the decelelation in m

Answer 1

here is your answer

given :

initial velocity (u) = 108 km/hr = 30 m/s

final velocity (v) = 36 km/hr = 10 m/s

time taken (t) = 4 seconds

to find = deceleration

solution :

by using first equation of motion

v = u+at

10 = 30+4a

4a = -20

a = -20/4

a = -5 m/s^2

so, deceleration is -5 m/s^2

Answer 2

Given, Initial velocity(u) = 108km/hr
=108×1000m/60×60s
=108×10m/6×6s
=3×10m/s
=30m/s
Final velocity(v)=36km/hr
=36×1000m/60×60s
=36×10m/6×6s
=10m/s

Time(t)=4sec

Acceleration (a) = ?

From Equations of motion we have,

»v=u+at
»10m/s=30m/s+a×4s
»10m/s-30m/s=4as
»-20m/s=4as
»-20m/s×4s=a
»a=-5m/s²

Therefore, deacceleration!= -5m/s²

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