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प्रश्न
A car of mass 800 kg, moving at 54 kmh−1 is brought to rest over a distance of 15 m. Find the retarding force developed by the brakes of the car.
उत्तर
Mass of car = m = 800 kg
Initial velocity of car = u – 54 kmh−1
u = `54xx5/18` ms−1 = 15 ms−1
Final velocity of car = v = 0
Distance covered = S = 15 m
Retarding force = F = ?
v2 – w2 = 2a S
(0)2 − (15)2 = 2a(15)
30 a = −225
a = `-225/30`
a = −7.5 ms−2
F = ma = (800) (−7.5)
F = −6000N
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