Question

Two Steel wires of the same length but radii `r` and `2r` are connected together end to end and tied to a wall as shown.

The force stretches the combination by `10 mm`. How far does the midpoint A move? (in mm)

Answer 1

Correct Answer - 8
`F/A_1=Y(/_l_1)/limplies/_l-1=(Fl)/(A_1Y)`
`F/A_2=Y(/_l_2)/limplies/_l-2=(Fl)/(A_2Y)=(Fl)/(4A_1)=8mm`
`/_l-1+/_l_2=10mm`
`(Fl)/(A_1y)+(Fl)/(4A_1Y)=10mmimplies (Fl)/(A_1Y)=8mm`