PART 1. SOLVING

Question 1

A tractor pulls a 1.0 meter wide heavy-duty offset disk harrow at an operating speed of 6 kph. What is the theoretical field capacity of the machine?

Answer 1

0.6 ha/hr

Question 2

A 13-cm wide animal-drawn plow having a speed of 3 kph and field efficiency of 70% is to plow a 1-hectare field. Determine the time required in plowing.

Answer 2

36.6 hrs

Question 3

If the puling load is 60 kg, what is the horsepower output of the animal?

Answer 3

0.66 hp

Question 4

A machine has an initial cost of P50,000 and a salvage value of P10,000 after 10 years. Find the book value after 5 years using straight-line depreciation.

Answer 4

P30,000

Question 5

What is the force required to pull a single moldboard plow on a clay loam soil having a width and depth of cut of 30 cm and 15 cm respectively. Soil draft is 8 psi.

Answer 5

253 kg

Question 6

A 4-cylinder four-stroke cycle engine with 3-in by 4-in cylinders develops 19 hp at 1650 rpm. Compute the ihp if the mechanical efficiency is 85%.

Answer 6

22.4

Question 7

A tractor has a wheelbase of 90 in and weighs 7800 lb. The static weight on the front wheels is 2,300 lb. Calculate the center of gravity longitudinally with respect to the front axle.

Answer 7

26.5 in

Question 8

A 6-nozzle boom sprayer is mounted at the back of a four wheel tractor. The nozzles are arranged 150 cm. apart along the boom length. Each nozzle has a 60 degree spray angle. At what height must the boom be raised, relative to the ground level, so that the spray from each nozzle does not overlap upon reaching the top of the rice plant canopy which is 50 cm tall?

Answer 8

180 cm

Question 9

If the tractor travels at 5 kph with 95% field efficiency, what will be the spraying capacity (in ha/hr) under the condition in the previous problem?

Answer 9

4.28

Question 10

What is the mechanical efficiency of an engine having a brake horsepower of 8 hp and an indicated horsepower of 10 hp?

Answer 10

80%

Question 11

If the compression ratio is 1:17, the piston displacement volume for 10 cm3 piston clearance volume is

Answer 11

160 cc

Question 12

What is the thermal efficiency of an engine which uses 0.6 lb of fuel per horsepower-hr? The fuel contains 20,000 BTU/lb.

Answer 12

21.2 %

Question 13

Wind is moving at 4 meters per second. If the rotor area is 2 square meters, what is the wind power

Answer 13

80 watts

Question 14

Determine the thermal efficiency of an engine which uses 0.6 lb of fuel for hp-hr, the fuel contains 20,000 Btu/lb.

Answer 14

21.21%