The graph shows the behaviour of a length of wire in the region for which the substance obeys Hook’s law. $P$ and $Q$ represent

A graph is shown between stress and strain for a metal. The part in which Hooke's law holds good is

Copper of fixed volume $V$ is drawn into wire of  length $l$. When this wire is subjected to a constant force $F$, the extension produced in the wire is $\Delta l$. Which of the following graphs is a straight line?

The adjacent graph shows the extension $(\Delta l)$ of a wire of length $1\, m$ suspended from the top of a roof at one end and with a load $W$   connected to the other end. If the cross-sectional area of the wire is $10^{-6}\, m^2$, calculate the Young’s modulus of the material of the wire.

The diagram shows the change $x$ in the length of a thin uniform wire caused by the application of stress $F$ at two different temperatures $T_1$ and $T_2$. The variations shown suggest that