Conservation Of Energy Flashcards

1
Q

Where is energy stored?

A

Pretty much anywhere

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2
Q

What energy is stored in food, fuel and batteries.

A

Chemical energy

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3
Q

What energy is stored in moving objects?

A

Kinetic energy

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4
Q

What energy is stored in hot objects?

A

Thermal energy

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5
Q

What energy is conserved in stretched, squashed or twisted materials?

A

Strain energy or elastic potential energy

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6
Q

What energy is conserved in high positions?

A

Gravitational potential energy

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7
Q

What an energy is conserved inside atoms?

A

Atomic energy or nuclear energy

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8
Q

Give 2 examples of energy being moved between different stores?

A

When an electric kettle is used to heat up water, energy transferred to the kettle by electricity ends up as a store of thermal in the hot water

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9
Q

Name 3 ways energy is transferred

A

Heating, electrically, by radiation

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10
Q

What can energy not be?

A

Created or destroyed

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11
Q

What can energy only be and what is this called?

A

It can only be transferred from one store to another, this is called the law of conservation of energy. The total energy transferred by the system is the same as the energy put into the system

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12
Q

What are the units for measuring energy?

A

Joules (J)

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13
Q

What happens to wasted energy in energy transfers?

A

Goes into the surrounding

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14
Q

Is energy always transferred into forms that are useful?

A

No, even though energy is always conserved, think of the kettle-the energy stored in the hot water is useful but the energy stored in the kettle itself and the surroundings is not

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15
Q

What shows the amount of energy transferred and what do the arrows represent?

A

A sankey diagram and the arrows represent the amount of energy in joules

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16
Q

Explain a way in which energy is transferred wastefully by mechanical processes

A

When a light bulb is switched on most of the energy supplied to it by electricity is transferred to the surroundings by heating. This energy is dissipated (it spreads out) and cannot be used for other useful energy transfers, it’s wasted

17
Q

How can you reduce unwanted energy energy transfers in mechanical processes?

A

If it’s friction you can reduce it by lubrication, or you can reduce it by finding ways to make sure all the energy is going to good use

18
Q

What is efficiency?

A

It is a way if describing how good a machine is at transferring energy into useful forms

19
Q

How can efficiency be increased?

A

Be reducing the amount of wasted energy

20
Q

What’s the formula for calculating energy efficiency?

A

Efficiency = useful energy transferred by the device ➗ total energy supplied to the device

21
Q

When energy is transfer by heating What is conduction?

A

Vibrations that are passed on between particles in a solid

22
Q

What are metals good?

A

Thermal conductors

23
Q

What are materials such as wood bad?

A

Thermal conductors but they are good thermal insulators

24
Q

In energy transferred by heating what is convection?i

A

It’s part of a fluid that is warmer than the rest

25
Q

How is energy stored?

A

In different ways

26
Q

What is the only way in high energy can be transferred through a vacuum?

A

Radiation. Infrared radiation can also pass through gases and some solid materials. Infrared radiation is absorbed and emitted easily by dark dull surfaces, and is absorbed and emitted poorly by light and shiny surfaces

27
Q

How do you reduce energy transfers?

A

Increasing thickness of a material, decreasing thermal conductivity and decreasing temperature difference

28
Q

Why is air a good thermal insulator?

A

Air is good thermal insulators because it has a very low thermal conductivity. When air is trapped it cannot from convection currents and so does not transfer much energy

29
Q

What is thermal conductivity?

A

Energy is transferred through materials by heating

30
Q

What happens when the thickness of a wall is thicker?

A

Less energy escapes

31
Q

How different factors affect the gravitational potential energy stored in an object?

A

Every time something is moved upwards, it stores more gravitational potential energy.
Any object that is above the surface of the earth contains a store of gravitational potential energy
The amount depends on the mass of an object, the strength of gravity and how far the object is moved upwards

32
Q

What’s the equation for gravitational potential energy?

A

Change in gravitational potential energy (j) = mass(kg) X gravitational field strength (n/kg) X change in vertical height (m)

33
Q

What factors affect the kinetic energy stored in an object?

A

mass, and it’s speed affect the amount of Kinect energy

34
Q

What’s the equation for Kinect energy?

A

Kinetic energy (j) = 1/2 X mass (kg) X (speed) squared, (m/s) squared

35
Q

How can you reduce energy transfers by heating?

A

Insulation slows down the rate at which energy is transferred out of the house by heating
When materials have a low thermal conductivity energy is not transferred very easily by heating
Materials containing air are good insulators because air has a very low thermal conductivity. When air is trapped it cannot form convection currents and so does not transfer much energy