Let ρ be the mass per unit length of the chain Ρ = m / l or, m = ρl Weight of hanging part = W2 = ρlg Weight of chain over the table = W1 = ρ( L-l) g For equilibrium, R = ρ( L-l) g---------------( i) f = W2 = ρlg μR = ρlg-------------------( ii)( i) Divided by( ii) gives 1 / μ =( L-l)/ l l = μL – μl l + μl = μL Therefore, l = μL /( μ + 1) Friction- A boon or Bane against motion Friction is a boon because of its advantages like:
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Friction helps in walking