Assertion A: For a given depth of cut, the output of a power shovel can be increased by decreasing the angle of swing.<br>Reason R: If the angle of swing is decreased, the cycle time will be decreased.

Consider the following statements for a power shovel:
(i) Output can be increased by reducing the angle of swing for a given depth of cut.
(ii) For a given angle of swing, output will be maximum at optimum depth of cut.
(iii) Output can be increased by keeping the depth of cut less than optimum depth.
(iv) Output can be increased by increasing the size of shovel.

A

(ii), (iii) and (iv) are correct

B

(i), (ii) and (iv) are correct

C

(i), (iii) and (iv) are correct

D

(i) and (iv) are correct

Assertion A: For a given depth of cut, the output of a power shovel can be increased by decreasing the angle of swing.Reason R: If the angle of swing is decreased, the cycle time will be decreased.

A

Both A and R is true and R is the correct explanation of A

B

Both A and R is true but R is not the correct explanation of A

C

A is true but R is false

D

A is false but R is true

The following data are provided for a surface mine to be excavated by a shovel:
Production target: 10000 te/shift
Available hours per shift: 6 hrs
Shovel loading cycles per hour: 10⁶
Bank density of the material mined: 2400 kg/m³
Swing factor at 120° swing: 0.91
Bucket fill factor : 0.64
Utilization of available time: 83%
No of working days in a year : 300
No of shifts per day : 3

The size of bucket of the shovel in m³ is

A

5.55

B

9.33

C

11.22

D

13.55

In an opencast mine loading and transporting has been carried out by shovel dumper combination. There is only one shovel is in operation. Dumpers arrive at the rate of 10 dumpers per hour and it takes shovel on an average 5 minutes to load a dumper. Assume arrival is Poisson and service time is exponentially distributed. Find the proportion of time the shovel is busy.

A

$$\frac{5}{6}$$

B

$$\frac{7}{8}$$

C

$$\frac{3}{4}$$

D

$$\frac{1}{2}$$

In an opencast mine loading and transporting has been carried out by shovel dumper combination. There is only one shovel is in operation. Dumpers arrive at the rate of 10 dumpers per hour and it takes shovel on an average 5 minutes to load a dumper. Assume arrival is Poisson and service time is exponentially distributed. Find the probability that the shovel is sitting idle.

A

$$\frac{1}{6}$$

B

$$\frac{1}{8}$$

C

$$\frac{1}{4}$$

D

$$\frac{1}{2}$$

If the output of a drag-line for 90° angle of swing at optimum depth of cut is X, then the output for 120° angle of swing at 120% of optimum depth of cut will be

A

Equal to X

B

More than X

C

Less than X

D

Any of the above

In an opencast mine loading and transporting has been carried out by shovel dumper combination. There is only one shovel is in operation. Dumpers arrive at the rate of 10 dumpers per hour and it takes shovel on an average 5 minutes to load a dumper. Assume arrival is Poisson and service time is exponentially distributed. What is expected idle time of a dumper in the system?

A

30 min

B

60 min

C

45 min

D

15 min

In an opencast mine loading and transporting has been carried out by shovel dumper combination. There is only one shovel is in operation. Dumpers arrive at the rate of 10 dumpers per hour and it takes shovel on an average 5 minutes to load a dumper. Assume arrival is Poisson and service time is exponentially distributed. What is expected waiting time of the dumper in the queue?

A

$$\frac{5}{7}$$ hour

B

$$\frac{5}{12}$$ hour

C

$$\frac{12}{7}$$ hour

D

$$\frac{1}{2}$$ hour

Output of a bulldozer is (i) Increased if drawbar HP of the tractor is increased for a given hauling distance (ii) Decreased if drawbar HP of the tractor is increased for a given hauling distance (iii) Increased if the hauling distance is increased for a given drawbar HP of the tractor (iv) Decreased if the hauling distance is increased for a given drawbar HP of the tractor

A

(i) and (iii) are correct

B

(i) and (iv) are correct

C

(ii) and (iii) are correct

D

(ii) and (iv) are correct

Output of a bulldozer is
(i) Increased if drawbar HP of the tractor is increased for a given hauling distance
(ii) Decreased if drawbar HP of the tractor is increased for a given hauling distance
(iii) Increased if the hauling distance is increased for a given drawbar HP of the tractor
(iv) Decreased if the hauling distance is increased for a given drawbar HP of the tractor

A

(i) and (iii) are correct

B

(i) and (iv) are correct

C

(ii) and (iii) are correct

D

(ii) and (iv) are correct

Assertion A: For a given depth of cut, the output of a power shovel can be increased by decreasing the angle of swing.
Reason R: If the angle of swing is decreased, the cycle time will be decreased.

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