Why is the dam of a water reservoir thick at the bottom?

What is $1$ Torr pressure? And what is $1$ bar?

$A$ vessel with a square cross-section and a height of $6 \ m$ is vertically partitioned. $A$ small window of $100 \ cm^2$ with a hinged door is fitted at a depth of $3 \ m$ in the partition wall. One part of the vessel is filled completely with water and the other side is filled with a liquid having a density of $1.5 \times 10^3 \ kg/m^3$. What force needs to be applied on the hinged door so that it does not open (in $N$)? (Acceleration due to gravity $= 10 \ m/s^2$)

Why do bags and suitcases have broad (wide) handles?

$A$ liquid $X$ of density $3.36 \ g/cm^3$ is poured into a $U$-tube, which contains $Hg$. Another liquid $Y$ is poured into the left arm with a height of $8 \ cm$. The upper levels of $X$ and $Y$ are at the same height. What is the density of $Y$ in $g/cc$?

In the figure, chamber $A$ contains a gas, a movable chamber $B$ is placed on top of the gas and it contains $n$ metal balls. The weight of chamber $B$ and the balls is supported by the gas. Chamber $C$ is a vacuum. Let the gas be in equilibrium at pressure $P$. Let $P^{\prime}$ be the pressure if one of the balls is taken away. Find $(P-P^{\prime}) / P$.