Water Temperature & Heat Measurement – Physics

Water Temperature & Heat Measurement – Physics

This chapter covers water temperature and heat measurement of physics.


change of a known mass of water

The amount of heat transferred can be determined by measuring the the temperature


calorie

The most commonly used unit for heat


to raise the temperature of 1 gram of water by 1 degree C

The calorie is defined as the amount of heat required


The kilocalorie

is 1000 calories ( the heat required to raise the temperature of 1 kilogram of water by 1 degree C)


Expansion of water

When water becomes ice, it expands. Ice has open-structured crystals resulting from strong bonds at certain angles that increase its volume. This make ice less dense than water.


Bimetallic Strip

Two, two strips of different metals welded or riveted together. because the two substances expand at different rates when heated or cooled, the strip bends; used in thermostats


Calorie

A unit of heat measurement used in nutrition to measure the energy value of foods. A calorie is the amount of heat energy needed to raise the temperature of 1 kilogram of water 1°C.


calorie

Amount of energy needed to raise temperature 1 gram of water 1 degree C


Degrees

A unit division of temperature.


Expansion Joints

separation joints in concrete and other things that allow the concrete to expand and contract


“Kilo”calorie

A unit of energy equal to 1,000 calories


Temperature

A measure of how hot (or cold) something is; specifically, a measure the measure of the average translational kinetic energy per particle in a substance.


Temperature

Quantity that tells how hot or cold something is


Matter expands

When temperature increases


Matter contracts

When temperature decreases


Temperature

is related to random motions of molecules in a substance


Temperature

is not a measure of total kinetic energy


Celsius Scale

The gap between freezing and boiling is divided into 100 equal parts, called degrees. This temperature scales is the


Water freezing

0 degrees Celsius


Water boiling

100 degrees Celsius


Fahrenheit scale

the temperature scale used commonly in the United States


Water freezing

32 degrees Fahrenheit


Water boiling

212 degrees Fahrenheit


Kelvin scale

the scale used in scientific research is the SI scale


absolute zero

0 kelvin


no kinetic energy to give up

At absolute zero a substance has


-273 Celsius

Zero on the Kelvin scale or absolute zero


1 liter

There is twice as much kinetic energy in 2 liters of boiling water as in


same

The temperature of both liters of water (the 2 boiling vs 1 not) are the same because the average kinetic energy of molecules in each is the


a warmer substance to a cooler substance

direction of spontaneous energy transfers is always from a


heat

energy that transfers from one object to another b/c of a temperature difference


heat

Matter contains energy in several forms but it does not contain


internal energy

thermal energy- the energy resulting from heat flow


thermal contact

When heat flows from one object or substance to another it is in contact with the objects or substances are said to be


flows from higher temperature into lower temperature

during thermal contact heat


average molecular kinetic energy difference

Heat flows based on


same temperature

After objects in thermal contact with each other reach the


thermal equilibrium

After object in thermal contact with each other reach the same temperature, no heat flows between them- we say the objects are in


only its own temperature

We then know the temperature of the thermometer is also the temperature of the substance. So a thermometer, interestingly enough, shows


internal movements of atoms within molecules

There is rotational kinetic energy of molecules and kinetic energy due to


there is also potential energy

due to force between molecules


internal energy

the grand total of all energies inside a substance


it contains internal energy

substances do not contain heat


Kilocalorie

The heat unit in rating foods is actually a __ although its often referred to as the calorie


caloric

heat was invisible and called


joules

heat is measured in, according the International System of Units


1 calorie equals 4.184 J

the relationship between calories and joules is that


joule equivalent

where an input of 4.184 joules raises the temperature of 1 gram of water 1 degree C


increases more

Although the same quantity of heat is added to both containers, the temperature of the container with the smaller amount of water increases more


released as heat

The energy value in food is determined by burning the food and measuring the energy that is


specified number of degrees

specific materials require quantities of heat to raise the temperature of a given mass of the material by a specified number of degrees


is responsible for increases in temperature

absorbed energy that increases the translation speed of molecules


increase the internal vibrations within molecules or stretch intermolecular

absorbed energy may also increase the rotation of molecules


Temperature

is a measure only of the kinetic energy of translation motion


translation fashion

iron atoms in the iron lattice primarily shake back and forth in


rotations, internal vibrations, and bond stretching

while water molecules soak up a lost of energy in


specific heat capactiy

water absorbs more heat per gram than iron for the same change in temperature, we say water has a higher


the specific heat capacity

of any substance is defined as the quantity of heat required to raise the temperature of a unit mass of the substance by 1 degree


thermal inertia

specific heat capacity is like___ since it signifies the resistance of a substance to change in its temperature


Water

has a much higher capacity for storing energy than most common materials


water is a very useful cooling agent

a relatively small amount of water absorbs a great deal of heat for a correspondingly small temperature rise, because of this


its temperature would rise higher for a comparable absorption of heat

If a liquid of lower specific heat capacity were used in cooling systems


water

takes longer to cool


improves the climate

the property of water to resist changes in temperature


water is warmer than the air

in the winter


water is cooler than air

in the summer


expansion

when the temperature of a substance is increased its molecules jiggle faster and normally tend to move farther apart


expand

solids, liquids, and gases _____ when they are heated and contract when they are cooled


gases

generally expand or contract much more than liquids


liquids

expand or contract more than solids


expansion

of materials must be allowed for in the construction of structures and devices of all kinds


Kelvin

0 K for Absolute Zero to 373 K for boiling point of water
– 0 at absolute zero; same size degrees as Celsius scale
– Kelvins, rather than degrees, are used


Heat

Internal energy transferred from one thing to another due to a temperature difference
•Internal energy in transit


Quantity of heat

Measured in joules or calories
4.18 joules of heat are required to change the temperature of 1 gram of water by 1 Celsius degree. 4.18 joules = 1 calorie


Energy ratings of foods and fuels are determined

from energy released when they are burned.


Unit of energy

US Customary System: Calorie or calorie, Metric: Joule


Specific heat capacity

Defined as the quantity of heat required to change the temperature of a unit mass of the substance by 1 degree Celsius


Thermal expansion

Due to rise in temperature of a substance, molecules jiggle faster and move farther apart.
Most substances expand when heated and contract when cooled.


Thermal Contact

state of two or more objects or substances in contact such that heat can flow from one to the other


Thermal Inertia

Tendency of a substance to resist change in temperature with the gain or loss of heat energy.


Thermal Equilibrium

The state of two or more objects or substances in thermal contact when they have reached a common temperature.


Thermostat

a regulator for automatically regulating temperature by starting or stopping the supply of heat. A common example of using a bimetallic strip


Absolute Zero

The lowest possible temperature that a substance may have – the temperature at which molecules of the substance have the minimum kinetic energy. Temp equal to 0K or -273°C


Internal Energy

The total of all molecular energies that are internal to a substance (Including Rotational, Vibrational and Translational Kinetic Energy)


bimetallic strip

brass expands or contracts more when heated or cooled than iron does so the strip bends as shown


thermostat

when the bimetallic coil expands, the mercury rolls away from the electrical contacts and breaks the circuit. when the coil contracts, the mercury rolls against the contacts and completes the electric circuit


Thermometer

Measures temperature by expansion or contraction of a liquid (mercury or colored alcohol)


Thermometer readings occur

when the thermometer and the object reach thermal equilibrium (having the same average kinetic energy per particle)


Celsius

scale named after Anders Celsius (1701 -1744).
-0C for freezing point of water to 100C for boiling point of water


Fahrenheit

scale named after G. D. Fahrenheit (1686-1736).
-32F for freezing point of water to 212F for boiling point of water


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