16.Three wires P,Q and R of the same material and length have radii 0.1 cm, 0.2 cm and 0.3 cm respectively. Which wire has the highest value of Young s modulus of elasticity ?

17.The increase in length on stretching a wire is 0.05%. If its Poisson s ratio is 0.4, the diameter is reduced by

18.A piece of copper wire has twice the radius of a piece of steel wire. The Young s modulus for steel is twice that for the copper. One end of the copper wire is joined to one end of the steel wire so that both can be subjected to the same longitudinal force. By what fraction of its length of the copper has increased by 1% ?

19.A wire of length L and radius r is clamped rigidly at one end. When the other end of the wire is pulled by a force F, its length increases by l . Another wire of the same material of length 4 L and radius 4r, is pulled by a force 4F. The increase in length will be

20.A wire extends by 1 mm when a force is applied. Double the force is applied to another wire of same material and length but half the radius of cross-section. The elongation of the wire in mm will be