Questions 111–120 of 650. Imported answers require independent review unless marked reviewed.

Topic practice 650 questionsPage 12 of 65

Question 46

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In a surface mine, blasting is carried out using electronic detonator and cartridge emulsion explosive with following details:
Burden = 3.5 m
Spacing = 4.5 m
Bench height = 10.0 m
Subgrade drilling = 1.0 m
Stemming = 4.0 m
Linear charge concentration = 16 kg/m
Cost of one detonator = Rs. 800
Cost of explosive = Rs. 30/kg
The cost of blasting material per cubic meter of blasted rock, in Rs., is ______ (rounded off to 2 decimal places).

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Question 47

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A pit slope has the following information:
Number of benches = 5
Height of each bench = 8 m
Bench slope angle = 70 degree
If width of one bench is 24 m and that of other four benches is 10 m each, the overall pit slope angle, in degree, is ________ (rounded off to 2 decimal places).

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Question 48

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A direct rope haulage has the following details
Output = 24 tonne/hour
Length of trip = 610 m
Gradient = 1 in 12
Capacity of mine car = 1.0 tonne
Tare weight of mine car = 0.5 tonne
Average rope speed = 1.694 m/s
Change over time of cars = 3 minute
Acceleration due to gravity = 10.0 m/s^2
Neglecting all frictional resistance and mass of the rope, the minimum power required, in kW, to raise the loaded mine cars is ______ (rounded off to 3 decimal places).

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Question 49

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A mine void of dimension 100.0 m x 2.0 m x 1.2 m is to be filled in 3 hours by hydraulic stowing. The sand to slurry ratio is 0.4. If the hydraulic fill factor is 0.9, the hourly consumption of water for the operation, in m^3, is____ (rounded off to 2 decimal places).

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Question 50

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A 2.5 tonne diesel locomotive hauls 5 mine cars upslope having a gradient of 1 in 20. The constant tractive force of the locomotive is 1800 kN. The gross weight of a car is 3 tonne. Acceleration due to gravity is 10.0 m/s^2. If the acceleration of the system is 0.5 m/s^2, the rolling resistance in kN/tonne is______ (rounded off to 3 decimal places).

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Question 51

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A longwall panel is to be developed in a flat seam at a depth of H m. The surface subsidence profile (s) of the area with the horizontal distance x is estimated as

where, S_ is the maximum subsidence at the centre of the panel, x is measured from the inflection point. The value of x is negative towards the panel centre and positive towards the panel boundary.
The ratio between the critical width of the panel and the depth is_____ (rounded off to 2 decimal places).

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Question 52

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The percent Fe content of a random sample consisting of five observations is shown.
62 | 64 | 63 | 60 | 61
If mean grade of the stockpile is estimated using the above data, the standard error of mean grade, in %, is _____ (rounded off to 3 decimal places).

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Question 53

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In a bord and pillar panel, a square pillar of size 35 m × 35 m (centre to centre) is extracted to form four equal square-shaped stooks as shown. The width of each gallery and crosscut is 5 m. The height of the working seam is 3 m. The reduction in safety factor after pillar splitting by using Bieniawski’s pillar strength formula, in %, is____ (rounded off to 2 decimal places)
Bieniawski’s pillar strength formula,

; where,

= strength of 0.9 m^3 of coal block,

= pillar width and

= mining height
Diagram for Mining Engineering question 53


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Question 54

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A five-member truss system is shown in the figure. The maximum vertical force P in kN that can be applied so that loads on the member CD and BC do NOT exceed 50 kN and 30 kN, respectively is________ (rounded off to 2 decimal places).
Diagram for Mining Engineering question 54


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Question 55

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The characteristic polynomial of a third order matrix, A, is given by

If one of the eigen values of A is 1, then sum of the other two eigen values is ______ (in integer)

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