Agricultural Operations Man-Hour Requirements

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Questions and Answers

What is the formula for calculating draft horsepower?

DHP = F x V (correct)

DHP = (F - V) / 76.2 kg

DHP = (F x V) / 76.2 kg

DHP = F x V / (76.2 kg - mT)

At what speed does a light horse typically pull a load to develop around 1 hp?

0.9 m/s

1.1 m/s

1.0 m/s (correct)

0.8 m/s

What would be the draft horsepower developed by an 800 kg buffalo pulling an 80 kg load at 0.9 m/s?

1.2 hp

0.5 hp

0.95 hp (correct)

0.45 hp

Which factor does NOT affect the draft horsepower of an animal?

Animal's diet Signup and view all the answers

What is the typical pulling efficiency observed when multiple draft animals are harnessed together?

Efficiency decreases Signup and view all the answers

Which of the following animals is likely to generate the least horsepower?

Donkey Signup and view all the answers

What happens if a harness is poorly designed or ill-fitting when using draft animals?

It can cause the animals to work harder and suffer physically Signup and view all the answers

What is the average pulling ability of a buffalo in kg?

60-80 kg Signup and view all the answers

What is the man-hour requirement per hectare for broadcasting?

3.3 hours Signup and view all the answers

If a farm is 10 hectares and requires broadcasting, how many total man-hours are needed?

33 hours Signup and view all the answers

Which operation has the highest man-hour requirement per hectare?

Hand weeding transplanted rice Signup and view all the answers

What is the range of man-hour requirement for tillage with a hoe?

100-300 hours Signup and view all the answers

How many persons are needed to operate a 10-hp hydro tiller for one day (8 hours)?

1 person Signup and view all the answers

What is the maximum number of kg/hr that a 5-hp IRRI axial-flow thresher can process with 4 men feeding it?

700 kg/hr Signup and view all the answers

What formula is used to calculate the area covered based on time to finish work?

A = M × T Signup and view all the answers

What is the man-hour requirement for 5-hp power tiller plowing wet soil?

20-40 hours Signup and view all the answers

How much draft can six horses provide if each horse can pull a load of 60 kg?

228 kg Signup and view all the answers

What is the factor for draft power when using four animals?

3.1 Signup and view all the answers

Which of the following is NOT a renewable power source mentioned?

Coal Signup and view all the answers

What mechanical device is used to convert potential energy from water into mechanical energy?

Water wheel Signup and view all the answers

Using renewable energy to replace fossil fuels primarily helps to mitigate what concern?

Global warming Signup and view all the answers

What total draft will five draft animals provide if the specific draft is 50 kg?

200 kg Signup and view all the answers

Which renewable power source can be generated from water located at high elevations?

Water power Signup and view all the answers

What is the factor multiplier for three draft animals?

2.5 Signup and view all the answers

What is a primary reason why domestic animals are still used for farm power?

Animal power is cheaper to produce than fuel Signup and view all the answers

What is a significant advantage of using animal power in farming?

Animals can provide multiple resources such as meat and milk Signup and view all the answers

Which of the following is a disadvantage of using animal power?

Animals require significant care and feeding Signup and view all the answers

How much power can a 1,200 lb horse typically develop?

0.8 to 1 hp Signup and view all the answers

What is the typical power range for farm animals?

0.7 to 1.3 hp Signup and view all the answers

What limitation affects the working conditions of animals in farming?

Animals require training and time to adapt to working conditions Signup and view all the answers

During the early times, what was the primary reference for determining power in farming?

The horse Signup and view all the answers

What can a well-trained horse exert for a short period?

An overload of over 100% for short distances Signup and view all the answers

What is the expression for determining the theoretical power available from falling water?

Pth = ρqgh Signup and view all the answers

Which variable does NOT affect the theoretical power available from falling water?

Water temperature Signup and view all the answers

What percentage of the theoretical power is the actual power typically reduced by due to losses?

60-80% Signup and view all the answers

If a turbine has an efficiency of 80%, how is it factored into determining the actual power available?

It is multiplied with Pth. Signup and view all the answers

In the given sample problem, what is the theoretical power available when 1 m³/s of water is falling at a head of 10 meters?

98,100 watts Signup and view all the answers

What is the acceleration due to gravity (g) value used in calculating water power?

9.81 m/s² Signup and view all the answers

How is the actual power (Pah) from falling water represented mathematically?

Pah = Pth * eff Signup and view all the answers

What is the density of water (ρ) used in the formulas for power calculation?

1000 kg/m³ Signup and view all the answers

Study Notes

Man-Hour Requirements for Agricultural Operations

Tillage with hoe requires 100-300 persons-hr/ha.
Water buffalo plowing flooded soil needs 30-60 persons-hr/ha.
Comb harrowing with water buffalo requires 40-60 persons-hr/ha.
Plowing wet soil with a 5-hp power tiller needs 20-40 persons-hr/ha.
A 10-hp hydro tiller uses 4.4 persons-hr/ha.
Broadcasting requires only 3.3 persons-hr/ha.
Hand weeding for transplanted rice demands 120-320 persons-hr/ha.
Harvesting rice with a sickle requires 60-80 persons-hr/ha.
A 5-hp IRRI axial-flow thresher can process 350-700 kg/hr with four workers.

Human Power Measurement

Power generated (Pg) can be calculated using the formula: Pg = 0.35 − 0.092 log t.
Man-hour requirement formula: Mh x A = M x T, where Mh = man-hour requirement per hectare, A = area, M = number of persons, and T = time in hours.

Example Problem for Rice Planting

For 10 hectares with 8 hours of work, calculate required labor based on broadcasting rates.

Advantages and Disadvantages of Animal Power

Advantages:
- Low maintenance cost and multi-purpose use (meat and milk).
- Availability, providing a buffer for emergencies.
- Flexible in size and adaptable to various tasks.
- Low initial investment and capacity for draft work, including manure production.
Disadvantages:
- Limited working hours due to fatigue and need for rest.
- High time investment for feeding, care, and management.
- Limited operational efficiency under heavy loads or adverse weather conditions.
- Requires training for effective management and utilization.

Determination of Animal Power

Horses are central for power calculations, with specific performance metrics based on weight:
- 1000 lb horse can deliver 0.67 to 0.83 hp.
- Larger horses (1,200 lb) can reach up to 1 hp.
- Power range for farm animals generally from 0.7 to 1.3 hp.

Draft Horsepower Calculation

Draft horsepower (DHP) formula: DHP = (F × V) / (76.2 kg - mT).
Example: An 800 kg buffalo pulling an 80 kg load at 0.9 m/s produces 0.95 hp.

Harnessing Efficiency of Draft Animals

Efficiency decreases with a higher number of animals:
- 1 animal = factor of 1.0.
- 6 animals = factor of 3.8.
Example problem calculating total draft from six horses producing 60 kg each results in a total draft of 228 kg.

Renewable Power Sources

Main sources include water, wind, solar, and biomass.
Renewable energy is vital for clean energy and reducing reliance on fossil fuels.

Water Power Generation

Generated from high-elevation water converted through turbines or water wheels.
Two types of water movement for power generation:
- Falling/flowing water due to gravity.
- Tidal movements propelled by lunar or solar gravity.

Determining Water Power

Theoretical power from falling water: Pth = ρqgh, where ρ = density, q = flow rate, g = gravitational acceleration, and h = height.
Actual power is typically 60-80% less than theoretical due to losses.
Example problem illustrating the calculation of theoretical power from 1 m³/s at a 10 m head yields 98.1 kW, with actual power calculated through efficiency resulting in 78.48 kW.

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Description

This quiz explores the man-hour requirements for various agricultural operations, including tillage, plowing, and harvesting. It also covers the calculations necessary to measure human power and labor needs for certain tasks, particularly in rice planting. Enhance your understanding of labor efficiency in agriculture with this insightful quiz.