# Physics - P1

Physics, P1a, P1b, P1c, P1d, P1e, P1f, P1g, P1h.

Temperature vs. Heat

Keeping Houses Warm

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## Temperature vs. Heat

Temperature

Temperature is how hot something is.

It is measured with a termometer.

The unit it is measured in is Degrees Celcius.

Heat

Heat is the state of being hot.

It is a form of energy.

The unit it is measured in is Joules (J) as it is energy.

Hot Object (High Temp) --(Heat Flow)--> Cold Object (Low Temp.

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## What About Hot Objects?, Thermometers & Thermogram

Heat Flow

In a cup of hot water, the heat of the water flows out to its surroundings until the liquid and the surroundings are the same heat.

Thermometers

In a thermometer it has the resovoir/bulb (where the liquid is originally held at the top). The liquid inside the thermometer has to be something like mercury or alcohol because the liquid has to expand when the temperature increases, also to contract when the temperature decreases.

Thermograms

Thermograms give an image of temperature. Blue is usually colder and yellows are normally hotter.

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## Heat and Energy and Temperature Changes.

Temperature change is directly proportional to heat energy i.e. the more heat energy supplied, the bigger the increase in temperature as long as the mass remains the same.

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## Specific Heat Capacity

Specific Heat Capacity Equation

c=E/(mT)

c is the CAPACITY

E is the ENERGY USED

m is the MASS

T is the TEMPERATURE CHANGE

To work out the energy used you can change the equation to:

E=mcT     *

*All letters mean the same.

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## Specific Latent Heat

Specific Latent Heat Equation

L=mcT/M

L is LATENT HEAT

m is the MASS

c is the CUP WITH WATER

T is TEMPERATURE CHANGE

M is the MASS OF ICE

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## Keeping Houses Warm

How do houses lose heat when it's cold?

- Roofs, windows, doors

- Leaving appliances on

- Standby lights

How can we improve that?

- Insulation (wall cavity, fibre glass)

- Double/triple glazed windows/ closing doors when leaving a room

- Grass on Roofs

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## The Cost of Saving Energy

Calculating Payback Time

Some energy saving methods cost a lot to install in the first place.

PAYBACK TIME = INSTALLATION COST

----------------------------

FUEL SAVING

You can work out the payback time by dividing their cost of installation by amount of money they save each year.

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## Efficiency

How to work out how efficient you energy saving method is:

The efficiency of a heating system tells you how much of the energy you put in actually comes out as heating energy.

EFFICIENCY = USEFUL ENERGY OUT

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TOTAL ENERGY IN

You can work out how efficient your energy saving method is by dividing the useful energy that you get out by the total energy you put in.

The better the efficiency, the less energy is wasted so the cheaper they are to run.

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