Thermal Energy (Chapter P2) Flashcards

1
Q

What is a system?

A

A system is an object or group of objects

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2
Q

What are all the different stores

A
Thermal store
Elastic store
Kinetic store
Gravitational store
Nuclear store
Chemical store
Electrostatic store
Magnetic store
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3
Q

What is the thermal store

A

Energy due to an object’s temperature. Thermal stores increase when the object gets hotter and decrease when it gets colder

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4
Q

What is the Elastic store

A

Energy due to an object having a greater/shorter length than its natural length. Elastic stores increase if the object is stretched or squashed from its natural shape and decrease if it returns to its natural shape.

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5
Q

What is the Kinetic store

A

Energy due to an object’s mass and speed. Kinetic stores increase if an object’s speed increases and decrease if an object is slowed down.

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6
Q

What is the Gravitational store

A

Energy due to an object’s height above the Earth’s surface. Gravitational stores increase if an object is lifted up and decrease if it falls down.

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7
Q

What is the Chemical store

A

Energy due to atoms combining in a chemical reaction.

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8
Q

What is the Electrostatic store

A

This is energy stored when similar charged objects are pushed together and when opposite charged objects are pulled apart.

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9
Q

What is the Nuclear store

A

This is energy associated with the nucleus of an atom. This changes if changes happen in the nucleus e.g. in a fusion reaction

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10
Q

What is the Magnectic store

A

This is the energy stored when like poles of a magnet are pushed closer together and unlike poles are pulled further apart.

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11
Q

What are the energy transfers

A
Forces doing work 
A flow of an electrical current
Heating
Light
Radiation
Sound waves
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12
Q

What is internal energy?

A

Internal energy is the total kinetic and potential energy of all the particles (atoms and molecules) that make up a system. The molecules’ kinetic store is related to how fast they are moving, and the molecules’ potential store is related to how far apart they are (their bonds).

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13
Q

What is the equation for change in energy

A

= mass x specific heating capacity x change in temp

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14
Q

What is specific heat capacity

A

The specific heat capacity of a substance is the energy (in J) needed to increase the temperature of 1 kg of a substance by 1 degree (or Kelvin can be used too)

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15
Q

What is accurate data?

A

Accurate data is data which is close to the true value

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16
Q

What is precise data?

A

Precise data is data in which repeated measurements show very little spread about the mean value.

17
Q

What is reproducible data?

A

If another person can get the same result with the same, or different method/equipment, then the data is reproducible

18
Q

What is repeatable data?

A

If the same person can get the same result with the same equipment and method then the data is repeatable.

19
Q

What is random uncertainty?

A

Random uncertainty causes measurements to be spread around a mean value. The effect of random uncertainty can be reduced by repeating and averaging data.

20
Q

What is systematic uncertainty?

A

Systematic uncertainty occurs when measurement is always too high or too low for each repeat. Usually because of an error in the equipment e.g a badly calibrated thermometer.

21
Q

What is a zero error?

A

This is a type of systematic uncertainty which occurs when a measuring instrument reads a value when it should say zero. E.g. a mass balance which doesn’t say zero when there is nothing on it.

22
Q

What factors affect the rate of cooling of a building?

A

The thickness of the building’s walls and the thermal conductivity of its insulation affect the rate of cooling.

23
Q

What is specific latent heat

A

The specific latent heat of a substance is the amount of energy (in J) required to change the state of 1 kg of the substance with no change in temperature.

The specific latent heat of fusion is the amount of energy required to change the state of 1 kg of a substance from solid to liquid with no change of temperature.

The specific latent heat of vaporisation is the amount of energy required to change the state of 1 kg of a substance from liquid to gas with no change of temperature.

24
Q

What is the equation for energy and latent heat

A

energy = mass x latent heat

25
What is thermal conductivity
How good a material is at transferring energy by conduction
26
What does a material with a high thermal conductivity mean
It is a good conductor and can transfer energy very quickly by conduction
27
What does the rate of energy transfer depend on in an insulating material
The temperature difference across the material The thickness of the material The thermal conductivity of the material
28
Where does most infrared radiation come from
The Sun
29
What is the wavelength of infrared waves
longer than visible light
30
What happens to the infrared levels when an object gets hotter
More infrared radiation is emitted
31
What is black body radiation
It is radiation emitted by a body that absorbs all the radiation going towards it
32
what happens if an object absorbs more infrared radiation than it emits
The temperature of it increases
33
What factors does the earth's temperature depend on
Absorption of infrared radiation from the Sun | The emission of radiation from the earth's surface and atmosphere
34
What is the equation for specific heat capacity
c = Energy transferred / mass x temp change
35
What is the unit for specific heat capacity
J/kg degrees
36
How does mass effect the rate at which an objects temperature increases
the greater the mass of an object, the slower its temperature increases
37
What can reduce the energy transfer in a house
``` Loft insulation Cavity wall insulation Double-glazed windows aluminium foil behind radiators external walls with lower thermal conductivity ```
38
what is cavity wall insulation
It is insulation material used to fill the gaps between 2 brick layers of an external wall