Practice portal › Laws of Motion › Friction: Blocks, Belts and Inclines
Asked in JEE Main 31st Jan 2nd Shift 2023 · Stopping distance and retardation
Idea: the retardation comes from the kinematics, and friction is the only thing causing it, so μ g=a.
a=(Δ v)/(Δ t)=(20-0)/5=4 m s⁻².
On level ground the frictional retardation is
(μ mg)/m=μ g.
μ g=4, so μ=4/(10)=0.4.
The 10 kg cancels, as it always does on level ground: a heavier body has more friction to overcome but proportionally more inertia, and stops in the same time.
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