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GCSE Physics > P1 - Conservation and Dissipation of Energy > Flashcards

P1 - Conservation and Dissipation of Energy Flashcards

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1
Q

What are some types of energy?

A
  • Kinetic Energy
  • Gravitational Potential Energy
  • Chemical Energy
  • Electrical Energy
  • Light Energy
  • Heat/ Thermal Energy
  • Sound Energy
  • Nuclear Energy
  • Elastic Energy
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2
Q

What are the 7 Energy Stores?

A
  • Chemical Potential Energy
  • Kinetic Energy
  • Gravitational Potential Energy
  • Thermal Energy
  • Nuclear Energy
  • Magnetic Energy
  • Elastic Potential Energy
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3
Q

What are the 4 ways energy can be transferred?

A

1) Heating
2) Waves
3) Electricity
4) Force - when a force moves an object.

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4
Q

What has heat/thermal energy?

A

Anything with a temperature above zero kelvins (-273°C).

-273°C = 0K
0°C = 273K
273°C = 546K
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5
Q

What has kinetic energy?

A

Anything that moves.

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6
Q

What has nuclear energy?

A

Anything that is released from nuclear reactions.

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7
Q

What has chemical energy?

A

Anything with stored energy that can be released by a chemical reaction. E.g food, fuel, coal etc….

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8
Q

What has gravitational potential energy?

A

Anything above the ground. E.g a book on a shelf.

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9
Q

What has elastic/strain Energy?

A

Anything that is *elastically deformed (stretched) - e.g rubber bands, springs

*elastically deformed = stretched when force applied, but will go back to its shape when the force deforming it is removed.

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10
Q

What has sound energy?

A

Anything noisy gives off sound energy. For example instruments or a television.

NOT A STORE - sound travels

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11
Q

What has light energy?

A

Anything that is luminess.

NOT A STORE - light travels

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12
Q

How can energy transfers between different stores be visually represented?

A

Flow diagrams

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13
Q

How would the energy transfers between the energy stores in a torch lamp be represented on a flow diagram?

How is the energy transferred through a torch?

A

Chemical (Batteries) —> Light + Heat

Energy transferred by an electric current in the wires.

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14
Q

What happens in terms of energy when a skateboarder goes up and down a ramp?

A

As the skateboarder goes up the ramp, the GPE store increases and the kinetic energy store decreases.

But, as the skateboarder comes back down the ramp, the KE store increases as more energy is transferred to the kinetic store from the GPE store - the GPE store decreases.

There is NO LOSS in energy - just transfers between stores.

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15
Q

What happens in the moment that a falling object hits the ground?

A

Energy stored in the kinetic store suddenly decreases at the moment of impact.

The energy is transferred as thermal energy (friction) and as sound.

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16
Q

What does the law of the conservation of energy state?

A

Energy cannot be created or destroyed, only transferred from one type to another.

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17
Q

What is a closed system?

A

A system where no energy transfers take place OUT OF or INTO the system.

Nothing is gained. Nothing is lost.

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18
Q

What would happen if a pendulum was placed in a vaccum? What about a non-vaccum room?

A

The pendulum would keep swinging forever as there are no air particles in a vaccum - meaning that there is no air resistance.

A pendulum in a non-vaccum room, will constantly have energy transferred into and out of the system (object) - and will eventually stop.

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19
Q

What is constant within a closed system?

A

The total energy within a closed system is always the same, before and after energy transfers within the system.

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20
Q

What is work?

A

Work is the amount of energy transferred when a force moves an object.

21
Q

What is the amount of energy transferred to an object equal to?

A

Energy Transferred = Work Done

If 20J of energy are transferred - that’s how much work has been done - 20J

22
Q

What is the equation for work done?

A

Work Done = Force x Distance

W = F x d

(J) = (N) x (m)

Work can only be done when something moves, otherwise the distance is 0 and anything x 0 = 0.

23
Q

What happens to the work that is done to overcome friction? Where is it transferred to?

A

Mainly transferred to the thermal store of the object by heating - and then to the surroundings.

E.g - when you rub your hands together, they become warm. The muscles are doing work to overcome the force of friction between the hands. This work is transferred as heat energy - this warms the hands.

24
Q

How does height affect Gravitational Potential Energy?

A

Gravitational Potential Energy (GPE) increases with altitude.

25
Q

Why does the GPE store of an object increase with height?

A

Work is being done to overcome the force of gravity.

Just like how work is done to overcome friction

26
Q

What is the equation used to calculate ΔGPE?

A

ΔGPE = mass x gravitational field x Δheight

J) = (kg) x (N/kg) x (m

27
Q

What is gravitational field strength of the earth?

A

9.8 N/kg

28
Q

What is the equation for Kinetic Energy?

A

Kinetic Energy = 1/2 x mass x (speed)^2

KE = 1/2mv^2

(J) = 1/2 x (kg) x (m/s)^2

29
Q

How do GPE and KE interact?

A

GPE = KE because the energy is constantly being transferred between the two.

Essentially this means:

mgh = 1/2mv^2

30
Q

If we know that GPE = KE, what can we workout?

A

The velocity of the object in the energy store.

Rearrange: mgh = 1/2mv^2

v^2 = 2gh
v = √2gh
31
Q

What is the equation for Elastic Potential Energy?

A

Elastic Potential Energy = 1/2 x spring constant x extension^2

EE= 1/2kx^2

(J) = 1/2 x (N/m) x (m)^2

32
Q

What is Useful Energy?

A

Useful energy is energy transferred to where it is wanted, in the way that is wanted.

33
Q

What is Wasted Energy?

A

Wasted Energy is the energy that is not usefully transferred.

34
Q

When does energy become less useful and is wasted?

A

As energy dissipates (spreads out) into the surroundings.

35
Q

What is most wasted energy transferred as?

A

Transferred as heat due to friction with the air.

36
Q

What is input energy?

A

The energy supplied to the device.

37
Q

What is output energy?

A

The useful energy transferred by a device.

38
Q

As well as the output energy, what else does the input energy include?

A

The wasted energy.

Input Energy = Output Energy + Wasted Energy

39
Q

What is the equation for Energy Efficiency?

A

Efficiency (%) = (useful output energy transferred / total input energy supplied) X 100

40
Q

Can a machine ever be 100% energy efficient?

A

No, energy will always be transferred into other stores.

41
Q

Name one way a machine can be adapted to increase the Energy Efficiency?

A

Lubrication is used to reduce friction.

42
Q

What is the useful and wasted energy for a lightbulb?

A

Useful: Light emitted.

Wasted: Heat emitted to surroundings.

43
Q

What is the useful and wasted energy for a hairdryer?

A

Useful: Heat energy of air and Kinetic energy.

Wasted: Sound energy and Heat energy heating the hairdryer itself.

44
Q

What are the 4 main uses of Electrical Appliances?

A

1) Heating
2) Lighting
3) Making objects move
4) Sound and visual images

45
Q

What is Power?

A

Power is the rate of the transfer of energy. The faster the rate, the more powerful something is.

46
Q

What is the equation for power?

A

Power = energy transferred / time taken

P = E/t

(W) = (J) / (s)

47
Q

What is the unit for power? What is 1W equal to?

A

Watts

1W = 1J/s

48
Q

What is the equation for Power wasted?

A

Power wasted = total input - useful power output

GCSE Physics (18 decks)

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