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RAC 40 > unit 1 quiz > Flashcards

unit 1 quiz Flashcards

1
Q

in ___ heat or hidden heat, heat is known to be added, but no temperature rise is noticed…

A

latent

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2
Q

psia at sea level under standard conditions is ___

A

14.696

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3
Q

the two common temperature scales used by air conditioning and refrigeration technicians are called ___ and ___

A

Fahrenheit and Celsius

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4
Q

the fahrenheit absolute scale is called the ___ scale

A

rankine

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5
Q

atmospheric pressure in inches of mercury(“hg) decreases ___ per 1000 feet increase in elevation

A

1 in. hg

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6
Q

a gauge that reads 0 psi when opened to the atmosphere are known as ___

A

compound/low side gauge

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7
Q

the celsius absolute scale is called the ___ scale

A

kelvin

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8
Q

the weight of a column of air at sea level at standard conditions is ___ psig

A

14.696

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9
Q

heating the vapor temperature above the boiling point is called ___

A

superheat

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10
Q

heat that changes the temperature of a substance is called ___ heat

A

sensible

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11
Q

what is the difference between a mercury barometer and an aneroid barometer

A

mercury barometers use liquid to measure pressure, while aneroid barometers rely on the mechanical movement of a flexible capsule

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12
Q

how many btus of heat are removed per hour when the water at a flow rate of 10 gallons per minute is cooled 15ºF (water weighs 8.33 lb per gallon)

A

74,970 btu/h
10 gallons
x 60
= 600 gallons
x 8.33 lb/ gallon
= 4998 lbs/h
x 15ºF
=74,970 btu/h

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13
Q

define conduction of heat

A

heat the travels from molecule to molecule

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14
Q

define radiation of heat

A

heat that travels through space heating the first solid object it touches

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15
Q

define a btu

A

how much heat to heat up 1lb of water

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16
Q

define convection of heat

A

heat that travels through air or substances

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17
Q

how many btus are required to change one pound of ice at 20ºF to steam at 220ºF
a. 6520 btu/h
b. 3912 btu/h
c. 2608 btu/h
d. 1304 btu/h

A

d. 1304 btu/h

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18
Q

the standard atmospheric pressure at sea level is
a. 29.83”hg
b. 29.60”hg
c. 29.92”hg
d. 29.71”hg

A

c. 29.92”hg

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19
Q

which of the following represents a different temperature than the other three
a. 15ºC
b. 59ºF
c. 475ºK
d. 519ºR

A

c. 475ºK

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20
Q

how many btus are required to change 5 pounds of ice at 20ºF to steam at 220º
a. 3912 btu/h
b. 6520 btu/h
c. 1304 btu/h
d. 2608 btu/h

A

b. 6520 btu/h

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21
Q

temperature can be thought of as
a. the amount of heat in a material
b. the weight of the total mass of the material
c. the density of the material
d. a description of the level heat

A

d. a description of the level of heat

22
Q

pure water boils at a temperature of 212ºF at which of the following standard conditions
a. 14.696 psi
b. 12.967 psi
c. 13.967 psi
d. 15.967 psi

A

a. 14.696 psi

23
Q

as the temperature of a material increases, the molecules in the material
a. travel farther
b. travel faster
c. slow down
d. travel in more of a parallel direction

A

b. travel faster

24
Q

how many btus must be removed from one pound of water at 200ºF for it to end up as ice at 30ºF
a. 144 btu
b. 526 btu
c. 313 btu
d. 828 btu

A

c. 313 btu

25
Q

the temperature on the celsius scale where all molecular activity stops is
a. -272.6ºC
b. -274.1ºC
c. -277.8ºF
d. -273ºC

A

d. -273ºC

26
Q

the amount of heat needed to change the temperature of a substance will vary with the type of substance. This heat quality is called the ___ of the substance
a. specific heat
b. latent heat
c. sensible heat
d. relative heat

A

a. specific heat

27
Q

the temperature on the fahrenheit scale where all molecular biology activity stops is
a. -460ºF
b. -450ºF
c. -462.96ºF
d. -0ºF

A

a. -460ºF

28
Q

the celsius equivalent of 80ºF is
a. 27.5ºC
b. 26.7ºC
c. 26.3ºC
d. 25.5ºC

A

b. 26.7ºC

29
Q

at standard conditions on the celsius scale, water will boil at
a. 32ºC
b. 100ºC
c. 0ºC
d. 212ºC

A

b. 100ºC

30
Q

of the following choices, the warmest temperature is
a. 303ºK
b. 20ºC
c. 501ºR
d. 77ºF

A

a. 303ºK

31
Q

psig indicates
a. pounds per square inch absolute gauge
b. pounds per square inch absolute gravity
c. pounds per square inch of pressure absolute
d. pounds per square inch of gravity

A

a. pounds per square inch absolute gauge

32
Q

a bourbon tube is often found in an
a. mercury thermometer
b. pressure gauge
c. aneroid barometer
d. mercury barometer

A

b. pressure gauge

33
Q

t/f the difference in the level of heat between two substances will determine the heat transfer rate between the substances

A

true

34
Q

t/f the difference in the volume of two substances will determine the heat transfer rate between the substances

A

false

35
Q

t/f when water at 212ºF boils, it is only absorbing latent heat

A

true

36
Q

t/f water at 0ºF has no heat energy or molecular activity

A

false

37
Q

t/f temperature difference does not affect heat transfer rate

A

false

38
Q

t/f the fahrenheit scale is used in the english measurement system by the united states

A

true

39
Q

t/f in order for water at 60ºF to boil, it must absorb both sensible and latent heat

A

true

40
Q

t/f water boils at 212ºC

A

false

41
Q

t/f the laws of thermodynamics can help us to understand what heat is all about

A

true

42
Q

t/f both sensible heat and latent heat transfers can be read with a thermometer

A

false

43
Q

in what direction does heat flow

A

heat flows upward and also follows the cold

44
Q

what company produced a compressor that was practically noiseless? it had no seals and internal moving parts. only a mercury column compressed the refrigerant gas as the entire unit rotated

A

savage arms company

45
Q

in 1939 what compressor company introduced the first successful semi hermetic field serviceable compressor

A

copeland

46
Q

the ancient people of ___ cooled liquids in porous earthen jars. these jars were set out in the dry night air. and the evaporation from the liquid seeping through the porous walls providing cooling

A

egypt/india

47
Q

the ___ were the first to store natural ice and snow to cool wine and other delicacies

A

chinese

48
Q

the temperature set point for and office should be at ___

A

72ºF or 73ºF

49
Q

in hawaii dept of health regulation the temperature for a chill box should be at what temp

A

35ºF-39ºF

50
Q

what are the two vents called that is in an office ac system

A

supply and return

51
Q

who is willis carrier and why is he important

A

founder of carrier
invented the pt chart

RAC 40 (10 decks)

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