A boat has a uniform cross-sectional area at the water line of $750{ \mathrm{m}}^2$. Fifteen cars of average mass $1200 \mathrm{kg}$ are driven on board. Calculate the extra depth that the boat sinks in water of density $1000 \mathrm{kg}{ \mathrm{m}}^{-3}$.

Figure shows the force- extension graph for a wire that is stretched and then released.

Force-extension graph for a wire.

(a) Which point shows the limit of proportionality?

Figure shows the force- extension graph for a wire that is stretched and then released.

Force-extension graph for a wire.

(b) Which point shows the elastic limit ?

Figure shows the force- extension graphs for four springs, A, B, C and D.

Force-extension graphs for four different springs.

(a) State which spring has the greatest value of force constant.

Figure shows the force- extension graphs for four springs, A, B, C and D.

Force-extension graphs for four different springs.

(b) State which is the least stiff.

Figure shows the force- extension graphs for four springs, A, B, C and D.

Force-extension graphs for four different springs.

(c) State which of the four springs does not obey Hooke's law.

List the metals in Table from stiffest to least stiff.

The Young modulus of various materials. Many of these values depend on the precise composition of the material concerned. $\left(\text{Remenber} 1\mathrm{GPa}={10}^9\mathrm{Pa}\right)$

Which of the non-metals in Table is the stiffest?

The Young modulus of various materials. Many of these values depend on the precise composition of the material concerned.$\left(\text{Remenber} 1\mathrm{GPa}={10}^9\mathrm{Pa}\right)$