A homogeneous block with a mass `m ` hangs on three vertical wires of equal length arranged symmetrically . Find the tensions of the wires if the middle wire is of steel and the other two are of copper . All the wires have the same cross - section . Consider the modulus of elasticity of steel to be double than that of copper .

Answer

B, C, D

Explanation

` 2T_(c)+T_(s) = mg` …(i)
` Delta l _(c) = Deltal_(s)`
`:. (T_(c) l_(c))/(A_(c)Y_(c)) = (T_(s)l_(s))/(A_(s)Y_(s))`
`:. T_(s) = 2T_(c)`
`( as Y_(s) = 2Y_(c), l_(s) = l_(c) , A_(s) = A_(c))`
or `T_(s) = 2T_(c) ` ….(ii)
Solving these two equations we get ,
` T_(c) = (mg)/4 ` and
`T_(s) = 2 T_(c)`