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  1. Consider a car moving along a straight horizontal road with a speed of 72 km/h. If the coefficient of static friction between the tyres and the road is 0.5, the shortest distance in which the car can be stopped is (taking g = 10 m/s²)
    1. 30 m
    2. 40 m
    3. 72 m
    4. 20 m
Correct Option: B

Here u = 72 km/h = 20 m/s; v = 0;
a = – µg = – 0.5 × 10 = – 5 m/s²
As v² = u² + 2as,

∴ s =
(v² - u²)
=
(0 - (20)²)
= 40 m
2a2 × (-5)



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