A lamp is suspended in equilibrium from a fixed support by three long identical wires.
The weight of the lamp causes each wire to have an extension of 
. The height 
of the lamp above the floor is measured. The middle wire suddenly breaks and the lamp falls a small distance as the extensions of the remaining two wires increase. The wires obey Hooke’s law. When the lamp is in equilibrium, the height of the lamp above the floor is measured again. What is the difference between the two values of ?
