# Soil Mechanics Questions and Answers – Well Hydraulics – Pumping In and Pumping Out Tests – 1

This set of Soil Mechanics Multiple Choice Questions & Answers (MCQs) focuses on “Well Hydraulics – Pumping In and Pumping Out Tests – 1”.

1. The specific yield Sγ is given by _______
a) (Vwy+V)*100
b) (Vwy-V)*100
c) (Vwy/V)*100
d) (Vwy*V)*100

Explanation: The specific yield Sγ of an aquifer is defined as the ratio of volume of water drained by gravity Vwy to the total volume V. It is expressed as percentage. The specific yield Sγ is an indication of the water yielding capacity of an unconfined aquifer.

2. The value of specific yield depends upon the shape of the pores.
a) True
b) False

Explanation: The specific yield Sγ is given by,
Sγ=(Vwy/V)*100. The specific yield Sγ is proportional to the volume of water drained. This implies that the value of specific yield depends upon the shape of the pores.

3. The specific retention SR is given by _______
a) (VwR+V)*100
b) (VwR-V)*100
c) (VwR/V)*100
d) (VwR*V)*100

Explanation: The specific retention SR of an aquifer is defined as the ratio of volume of water retained VwR to the total volume V. It is expressed as percentage.

4. The relation between porosity n, specific retention SR, specific yield Sγ is __________
a) n= SR-Sγ
b) n= SR+Sγ
c) n= SR*Sγ
d) n= SR/Sγ

Explanation: The porosity n, specific retention SR, specific yield Sγ is given by,
Sγ=(V/V)*100 and SR=(VwR/V)*100
Vw= V+ VwR
But n=(Vw/V)*100
∴ n= SR+Sγ.

5. In the storage coefficient, the unit change in the component of the head is measured in _________ to the surface.
a) normal
b) tangential
d) inclined at 30°

Explanation: The storage coefficient is defined as the volume of water that an aquifer releases per unit surface area per unit change in the component of head normal to that surface.

6. The coefficient of transmissibility is defined as the rate of flow of water through a horizontal strip of unit width and full saturation height under unit hydraulic gradient.
a) True
b) False

Explanation: For a fully saturated soil mass of unit width extending to depth infinity, the discharge through it is known as the coefficient of transmissibility when the hydraulic gradient is unity.

7. If b is the aquifer thickness, the relationship between coefficient of transmissibility T and coefficient of permeability is ________
a) T=bk
b) T=b/k
c) T=b+k
d) T=b-k

Explanation: The coefficient of transmissibility T equals the coefficient of permeability k multiplied by the aquifer thickness b.
T=bk.

8. The drawdown, corresponding to a steady discharge, are observed at a number of wells in _______
a) pumping out test
b) pumping in test

Explanation: The permeability can be determined by pumping out test. Pumping must continue at a uniform rate for a sufficient time to approach a steady state condition.

Sanfoundry Global Education & Learning Series – Soil Mechanics. 