The thickness of a hollow metallic cylinder is $2 \mathrm{cm}$. It is $70 \mathrm{cm}$ long with outer radius of $14 \mathrm{cm}$. Find the volume of the metal used in making the cylinder, assuming that it is open at both the ends. Also, find its weight if the metal weighs $8\mathrm{g}$ per ${\mathrm{cm}}^3$.

Radius of a cylinder is $\mathrm{r}$ and the height is $\mathrm{h}$. Find the change in the volume if the height is doubled.

Radius of a cylinder is $\mathrm{r}$ and the height is $\mathrm{h}$. Find the change in the volume if the height is doubled, and the radius is halved.

Radius of a cylinder is $\mathrm{r}$ and the height is $\mathrm{h}$. Find the change in the volume if the height remains the same, and the radius is halved.