单项选择题The rate of heat transfer from a hot region to a cold region is affected most by the ().

A.size of the heat sink
B.temperature difference between the regions
C.size of the heat source
D.total heat of the system


您可能感兴趣的试卷

你可能感兴趣的试题

1.单项选择题A gradual decrease in the discharge pressure of an operating hydraulic pump can be caused by ().

A.the four-way control valve failing to shift
B.the bleeder valve sticking in the open position
C.cold hydraulic fluid
D.a clogged air vent falter on the oil reservoir

2.单项选择题If you are given the job of adding hydraulic fluid to a mooring winch, and are not certain as to the type of fluid to use, you should ().

A.add fluid that is the same color as the fluid in the reservoir
B.add turbine oil because it is always a good substitute
C.add any oil that has the same viscosity as the hydraulic fluid
D.check the winch manufacturers instruction book

3.单项选择题The output volume of a positive fixed displacement pump can be changed only by ().

A.changing the angle of the tilting plate
B.changing the speed of the pump
C.moving the slide block and rotor
D.moving the shaft trunnion block

4.单项选择题An excessive charge of refrigerant in an air-cooled refrigeration system can cause ().

A.oil foaming in the compressor
B.higher than normal suction and discharge pressures with a higher box temperature
C.higher than normal discharge pressure with a normal box temperature
D.the compressor to run continuously

5.单项选择题When the steering gear is in operation, you should ().

A.check hydraulic oil levels every hour
B.check the rams for overheating
C.check for excessive oil leakage from rams
D.drain water from telemotor cylinders each watch

6.单项选择题The oil in a cargo winch gear box should be sampled periodically to ().

A.prevent the gear box from leaking
B.prevent the oil from becoming inflammable
C.make sure it has not become contaminated
D.make sure the motor bearings are lubricated

7.单项选择题A spur gear pump should be operated with the discharge valves ().

A.slightly opened
B.throttled
C.fully opened
D.halfway opened

8.单项选择题The capacity of a centrifugal pump can be increased by the installation of a larger diameter impeller Another means of increasing the pump capacity is to ().

A.increase speed
B.increase the size of the cardent assembly
C.reduce wearing ring clearances
D.change the pump to a "close coupled" arrangement

9.单项选择题Which of the following forms of energy is demonstrated through the process of combustion?()

A.Chemical energy
B.Mechanical energy
C.Thermal energy
D.Electrical energy

10.单项选择题While inspecting the steering system at sea, you should check for ().

A.air bubbles in the sight glass
B.any leaks in the system
C.over-travel in the rudder angle indicator
D.lost motion in the rams