Energy Flashcards

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1
Q

Energy is _______ between stores

A

transferred

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2
Q

When energy is transferred to an object, energy is…

A

stored in of the object’s energy stores

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3
Q

When a system changes, what happens?

A

Energy is transferred

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4
Q

What is a system?

A

An object or group of objects

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5
Q

What are closed systems?

A

Systems where matter and energy cannot enter or leave

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6
Q

What is always the net change in total energy of a closed system?

A

Always 0

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7
Q

A simple pendulum has what type of motion?

A

Oscillating motion

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8
Q

In a simple pendulum, what is the energy transferred between?

A

Kinetic energy and gravitational potential energy

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9
Q

Work done = ___ ______

A

Energy transferred

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10
Q

Give 3 examples of work being done

A
  • Initial force excerted by person to throw a ball upwards does work
  • Friction between car’s brakes and its wheels does work (as car slows down)
  • Collision between car and stationary object = normal contact force between car and object does work
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11
Q

What is the energy transfer for when a person throws a ball upwards?

A

Chemical energy → Kinetic energy

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12
Q

What is the energy transfer for when a car brakes?

A

Kinetic energy → Thermal energy

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13
Q

What is the energy transfer for when a car collides with a stationary object?

A

Kinetic energy → Elastic potential + thermal energy + sound energy

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14
Q

Energy can be ______ usefully, _____ or _______

A

Energy can be transferred usefully, stored or dissipated

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15
Q

Energy cannot be ______ or _____

A

Created or destroyed

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16
Q

Less energy that’s ‘wasted’, more _____ device is

A

efficient

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17
Q

Name 3 ways we can improve the efficiency of energy transfers?

A
  • Insulating
  • Lubricating
  • Streamlining objects
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18
Q

How do friction and air resistance dissipate energy?

A

By heating the surroundings

19
Q

How can the flow in a system be represented?

A

By using Sankey diagrams

20
Q

Energy in kinetic energy store depends on object’s _____ and _______

A

mass and speed

21
Q

Greater an object’s mass + faster it’s going, the more

A

kinetic energy it has

22
Q

Raised objects have…

A

gravitational potential energy

23
Q

Higher the object raised = the more

A

gravitational potential energy / energy transferred to its store

24
Q

Stretching can transfer energy to ____ _______ ______ stores

A

elastic potential energy

25
Q

What is power?

A

The rate of energy transfer OR the rate of doing work

26
Q

1 Watt = …

A

1 joule of energy transferred per second

27
Q

What makes a machine powerful?

A

If it can transfers a lot of energy in a short space of time

28
Q

What is conduction?

A

Process where vibrating particles transfer energy to neighbouring particles

29
Q

In conduction, how is energy transferred to object?

A

By heating

30
Q

In conduction, what store of an object is the energy transferred to?

A

Transferred to its thermal store & shared across kinetic energy stores of particles

31
Q

In conduction, what happens to particles when they’re heated up (mention collsions + how it leads to conduction)?

A
  • Particles heated vibrate more and collide with each other
  • These collisions cause energy to be transferred between particles’ kinetic energy stores
  • = conduction
32
Q

What is thermal conduction?

A

A measure of how quickly energy is transferred through a material

33
Q

What do materials with high therma conductivity do?

A

Transfer energy between their particles quickly

34
Q

What is convection?

A

Where energetic particles move away from hotter to cooler regions

35
Q

In convection, how is energy transferred to object?

A

By heating to thermal store of liquid or gas

36
Q

Why can metal conduct heat?

A

Particles are tightly packed and have free electrons which can move and carry heat

37
Q

What do insulators do?

A

Reduce heat movement by conduction

38
Q

Illustrate the particle arrangement in a conductor

A
39
Q

Illustrate the particle arrangement in a insulator

A
40
Q

Explain why insulators do not conduct heat easily

A
  • Particles not tightly packed and there’s massive spaces between them
  • ∴ When particles vibrate = vibrations (heat energy) cannot be passed onto nearby particles easily
41
Q

Explain why hot air is more dense

A
  1. Heated particles move faster and space between individual particles increase
  2. Causes density of region being heated to decrease
42
Q

Why does warmer and a less dense region (particles) rise above a denser, cooler region (particles)? (simple answer)

A

Because fluids can flow

43
Q

When is a convection current created?

A

If there’s a constant heat source