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Physics · LAWS OF MOTION
हिन्दीA car is traveling along a straight horizontal road at a constant speed \( v = 20\text{ m/s} \). A box of mass \( m = 20\text{ kg} \) rests on the flat horizontal floor of the car. The coefficient of static friction between the box and floor is \( \mu_s = 0.4 \). Taking \( g = 10\text{ m/s}^2 \), the minimum stopping distance over which the car can be stopped with constant retardation without causing the box to slide is:
Correct answer · Option 3
50 m
Explanation
Maximum retarding acceleration without slipping is \( a_{\max} = \mu_s g = 0.4 \times 10 = 4\text{ m/s}^2 \). Minimum stopping distance \( s = \frac{v^2}{2 a_{\max}} = \frac{20^2}{2 \times 4} = 50\text{ m} \).
