Question

a car mass 200 kg moving a 36 km per hour is brought to rest after it covered a distance of 10 M find the retarding force acting on car

Answer 1

Mass = m = 200kg

intial velocity = u = 36km/hr = 36000m/3600s = 10m/s
k
final velocity = v = 0 km/hr = 0m/s

distance = s = 10m

acceleration = a = ?

Force = F = ?
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v²-u² = 2as

(0)²-(10)² = 2(a)(10)

0-100 = 20a

-100/20 = a

-5 m/s² = a
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F = ma

F = 200kg × -5m/s²

F = -1000kgm/s²

F = -1000N

F = -10³N

F = -1 KN
(here minus sign shows that force acting apposite of objects motion )

so force acting on the car is -1 kilo newton. or -1000 newton
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