# Strength of Materials Questions and Answers – Rectangular Dam Analysis

This set of Strength of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Rectangular Dam Analysis”.

1. Calculate the self-weight of the masonry of the rectangle dam of 10 m height and 4 m wide. Consider specific weight of masonry as 20kN/m3.
a) 600 kN
b) 500 kN
c) 800 kN
d) 1000 kN

Explanation: Self weight of masonry = W = Area of cross-section × 1× Specific weight of masonry.
= (10×4)×1×20 = 800 kN.

2. Water-cement ratio varies normally from ______________ to __________
a) 0.42 – 0.45
b) 0.45 – 0.48
c) 0.42 – 0.48
d) 0.45 – 0.5

Explanation: The ratio to which the required amount of water is added to weight of cement to obtain desired consistency and workability of concrete mix is known as water cement ratio. It varies from 0.42 to 0.48.

3. Calculate the resultant force of dam with given self weight 800kN and water pressure be 500kN.
a) 943.4 kN
b) 956.7 kN
c) 948.6 kN
d) 939.1 KN

Explanation: Resultant force (R) = (P2 + W2)1/2 = 5002 + 8002.
= (5002 + 8002)1/2
= 943.39 ~ 943.4 kN.

4. When the reservoir is empty tension occurs at ___________
a) Toe
b) Heel
c) Top width
d) Bottom width

Explanation: For no tension to develop in the damn section in any condition, the eccentricity should be less than b/6. When the reservoir is empty, tension occurs at toe and compression occurs at heel.

5. What is the mix proportion for M15 grade concrete?
a) 1:1:2
b) 1:2:4
c) 1:3:6
d) 1:4:8

Explanation: Mix proportion for M15 grade concrete is 1:2:4.

M10 1:3:6
M15 1:2:4
M20 1:1.5:3

6. Laterite is an example of ___________ rock.
a) Siliceous
b) Argillaceous
c) Calcareous
d) Metamorphic

Explanation: The Rocks having (Gneiss) aluminium or clay as the main component, such rocks are known as argillaceous rocks. Example: Slate, Laterite.

7. ________ is crystalline and compact in structure.
a) Marbles
b) Granite

Explanation: Marble is a metamorphic rock and is made from limestone, this is a very costly stone. It is less durable. It is crystalline and compact in structure. So it can take a fine polish. It is not very hard.

8. As per IS, the standard dimensions for a brick is _______ (in cm).
a) 19×8×8
b) 19×9×8
c) 19×9×9
d) 19×8×9

Explanation: The shape of a brick should be uniform with rectangular surface and its size should be standard with 19×9×9 cm. They should have a uniform red colour and it should be well burnt.

9. Formation of white patches on the surface on the bricks is ____________
a) Tempering
b) Porosity
c) Shrinkage
d) Efflorescence

Explanation: A good brick should not contain excess alkaline soils when the bricks are exposed to the atmosphere. It should not absorb moisture. If it attracts moisture then dampness occurs and results in the formation of white patches. Hence the brick begins decaying.

10. Kiln burning involves 90% of first class bricks.
a) True
b) False

Explanation: Kiln burning is a permanent structure. There is complete control on fire. It produces a large scale of manufactured bricks, it takes only 24 hours in burning the bricks and 12 days for cooling. It produces 90% of burnt bricks.

11. ______ bricks can withstand up to a temperature of 1800°C.
a) Refractory
b) Fly ash
c) Clay
d) Cement

Explanation: The bricks made from refractory clay are called refractory bricks. The weight of these bricks is 2 kN/m3. The standard size is 230× 65× 113 mm. These bricks can withstand up to the temperature of 1800°C.

12. According to IS, the minimum expansion joint in construction should be ________
a) 18mm to 30 mm
b) 15mm to 24mm
c) 18mm to 25mm
d) 22mm to 30mm

Explanation: According to Indian standards 456- 2000, it is desirable to provide 18 mm to 25 mm thick expansion joints after every 30 to 45 m construction of length.

13. The edges formed by the intersection of plane surfaces of a brick are known as _________
a) Arises
b) Stretcher
d) Frog

Explanation: In any bond, the edges formed by the intersection of plane surfaces of a brick are termed as arises. These are straight and sharp in case of good bricks or brick tiles.

14. The depression made in the face of brick during its manufacture is _________
a) Brick tile
b) Bat
c) Frog
d) Quoin closer

Explanation: The depression provided on any face of the brick during its manufacture can be termed as frog. A hand moulded bricks has one frog. A pressed brick has two frogs.

15. Calculate the eccentricity of a rectangular dam of width 4 m. Take the distance between the water face and point where resultant cuts the base as 5.25 m.
a) 2.25m
b) 3.25m
c) 4.35m
d) 5.35m

Explanation: Eccentricity = e = Z – b/ 2
Where Z = 5.25 m & b = 4m ; Now, e = Z- b/2
e = 5.25 – 4/2
= 3.25m.

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