Galvanised iron sheets are commonly used as a roofing material. These are very durable and fire proof. The main disadvantage is y are not sound proof.

A pump is a mechanical device which converts mechanical energy into hydraulic energy. The hydraulic energy is in form of pressure energy. The pumps are generally used for lifting liquid from a lower level to a higher level.

Explanation:

We know,

$\frac{M}{I}=\frac{{\sigma }_b}{y}=\frac{E}{R}$      .......(1)

$R=\frac{EI}{M}$     .......(2)

Here, R = Radius of curvature, E = Elastic modulus of beam, I = Area Moment of Inertia, M = Bending moment at cross-section of beam

From (2), it is clear that

• If M is variable, n radius of curvature of beam is variable and shape of elastic curve is parabolic
• If M is constant, n radius of curvature of beam is constant and shape of elastic curve is a circular arc
• If M is zero, n radius of curvature of beam is infinite and shape of elastic curve is a straight line

Barrages are much more costly than weirs. Gates are raised off high flood to pass floods. They have perfect control of river flow.

When two dissimilar shafts are connected toger to form one shaft n shaft can be termed as composite shaft.

Combined catchment area is defined as total catchment area which contributes water in to stream or a tank. Combined Catchment area = Free catchment area + intercepted catchment area.

A structure constructed at head of canal to regulate supply of water into canal is called ?Head Regulator?. The functions:
i. It is used as a measuring device.
ii. It controls entry of silt into canal.

For solid shaft Z = J/R = ?/32 � D⁴/ D/2.
Z = ?/16 D³.

The ratio of area of a jet at vena contracta to area of orifice is known as coefficient of contraction. The value of Cc varies from 0.61 to 0.69 for different orifices. Generally, for sharp edged orifice value of Cc may be taken as 0. 64.

River gauging station site should be selected in such a way that site should be stable and re should not be any choice of scouring and silting. At gauge site, river section should be at right angles to flow of river.