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physics > P1 - Conservation And Disspation Of Energy > Flashcards

P1 - Conservation And Disspation Of Energy Flashcards

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1
Q

What is chemical energy and how does it transfer energy

A

Chemical energy stores include food, fuels, or chemicals found in batteries. (Energy is transferred during chemical reactions.)

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2
Q

Name as many energy stones.

A

-Magnetic
-Internal (thermal)
-chemical
-kintetic
-electrostatic
-gravitational potential
-nuclear
- Elastic potential

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3
Q

What is thermal energy

A

The energy a substance has because of its temperature.

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4
Q

What is kinetic energy

A

The energy an object has because it is moving.

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5
Q

What is gravitational potential energy?

A

Energy stoned in an object because of its position.

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6
Q

Describe the changes to the energy store when a torch is switched on. (4)

A
  • Chemical energy store in battery
  • electrical current in wires
  • energy transferred to the surroundings
  • light waves & increase in the thermal energy stare of surroundings
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7
Q

What is the conservation of energy?

A
  • Energy cannot be created nor destroyed; only transferred
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8
Q

What is a closed system?

A
  • System where no energy transfers take place out of or into the energy stores of the system.
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9
Q

Describe the changes to the energy stores in a system.

A

Energy can transferred between energy stones within a closed system
The total energy of a system is always the same (before. & after, any such changes.

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10
Q

Why is the conservation of energy A very important idea?

A

? IDEK

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11
Q

What does work mean in science?

A

Work is done on an object when a force makes the object move.

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12
Q

How is work and energy related?

A

Because , energy transferred = work done

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13
Q

What happens to work done to overcome friction?

A

Work done to overcome friction is transferred as energy to the thermal energy stores of the object that rubs together and to the surroundings

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14
Q

What at happens to the gravitational potential energy store of an object when it moves up or down.

A

Gravitational potential energy stone of an object increases when it moves and decreases when it moves down

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15
Q

Why does an object moving up has an increase in its gravitational potential energy?

A

Because work is done on it to overcome the gravitational force.

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16
Q

Why is in easier to lift an object on the moon than on the earth.

A

Because the gravitational field strength on the moon is lower than on earth

17
Q

What does the amount of energy in kinetic energy store depend on.

A

The energy in the kinetic energy store of a moving object depends on its mass and speed.

18
Q

What is the elastic potential energy store

A

The energy stored in an elastic object when work is done on the object.

19
Q

What is useful energy?

A

Useful energy = energy transferred to where it’s wanted in the way that is wanted.

20
Q

What’s wasted energy?

A

Wasted energy = energy that’s not usefully transferred.

21
Q

What eventually happens to wasted energy?

A

Wasted energy is eventually transferred to the surroundings.

22
Q

Is energy still as useful after it is used?

A

As energy dissipates (spreads out) , it becomes less useful.

23
Q

What is the maximum efficiency of any transfer.?

A

100%

24
Q

How do machines waste energy?

A

Machines waste energy because of friction between their moving parts, air resistance, electrical resistance and noise.

25
Q

How can energy transfers be made more efficient.

A

Machines can be made more efficient by reducing the energy they waste. For example, lubrication is used to reduce friction between moving parts.

26
Q

How is energy supplied to your home?

A

Supplied by electricity, gas and oil.

27
Q

State the useful & wasted energy in a hairdryer.

A

useful energy = Kinetic energy of the air driven by the fan
wasted energy = sound of the fan motor (sound energy) & heating the hairdryer itself

28
Q

Why are electrical appliances so useful?

A

Electrical appliances can transfer energy in the form of useful energy at the flick of a switch.

29
Q

What are most everyday electrical appliances are used for?

A

Includes hearing, lighting, making objects move (using an electric motor, and producing sound & visual images.

30
Q

How to choose an electric appliance for a particular job,

A

Choose an electric appliance designed for a particular purpose and wastes as little energy as possible.

31
Q

What is meant by power?

A

Power is the rate of transfer of energy.

32
Q

What is meant by efficiency?

A

Efficiency =
Useful output energy transferred by device(joules)/ total input energy supplied to the device.

physics (4 decks)

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