Topic 1 - Motion, Forces and Conservation of Energy Flashcards Preview

Physics (Paper 1: 1-3, Paper 2: 4-7) > Topic 1 - Motion, Forces and Conservation of Energy > Flashcards

Flashcards in Topic 1 - Motion, Forces and Conservation of Energy Deck (93):
1

Define acceleration

The change in velocity in a certain amount of time

2

Formula for average acceleration

(initial velocity - final velocity) / time

3

Define deceleration

Negative acceleration (slowing down at a constant rate)

4

Define uniform acceleration

The same as a constant acceleration

5

Describe what a slope in a distance/time graph shows you

Speed

6

Describe what a flat section in a distance/time graph shows you

The object has stopped

7

Describe what a steeper line in a distance/time graph shows you

It's going faster

8

Describe what a curve in a distance/time graph shows you

Acceleration
-A curve getting steeper means it's speeding up
-A curve levelling off means it's slowing down

9

Describe what a slope in a velocity/time graph shows you

Constant acceleration

10

Describe what a flat section in a velocity/time graph shows you

Steady speed

11

Describe what a downhill slope in a velocity/time graph shows you

Constant deceleration

12

Describe what a curve in a velocity/time graph shows you

Changing acceleration

13

State how you can find the distance travelled in a velocity/time graph

Find the area under the part of the graph you want to find out

14

State Newton's First Law

If the resultant force on a stationary is zero, the object will remain stationary. If the resultant force on a moving object is zero, it will carry on moving at the same velocity

15

The force and the acceleration are...

Directly proportional

16

The acceleration and the mass are

Inversely proportional

17

State Newton's Second Law (resultant force formula)

Resultant force = mass x acceleration

18

Define mass

-The amount of 'stuff' in an object
-It's scalar quantity

19

Define weight

The force acting on an object due to gravity

20

Formula for weight

Weight = mass x gravitational field strength

21

State the gravitational field strength for earth

10 N/Kg

22

Define velocity

The speed and direction of an object

23

Explain circular motion

-If an object is travelling in a circle (at a constant speed), it is constantly changing direction, so it is constantly changing velocity. This means that it is accelerating
-This means that there must be a resultant force acting on it
-This force acts towards the centre of the circle

24

Define centripetal force

The force that keeps something moving in a circle

25

Define inertia

The tendency for an object to keep moving with the same velocity

26

Define inertial mass

An object's inertial mass measures how difficult it is to change the velocity of an object

27

Formula for inertial mass

Force / acceleration

28

State Newton's Third Law

When two objects interact, the forces they exert on each other are equal and opposite

29

Define momentum

A property that all moving objects have

30

Formula for momentum

Mass x velocity

31

The more momentum an object has...

The greater the mass or velocity of an object

32

State what conservation of momentum is

In a closed system, the total momentum before an event (e.g. a collision) is the same as after the event

33

State what causes a change in momentum

When a resultant force acts on an object for a certain amount of time

34

Formula for change in momentum

Change in momentum / time

35

The faster a given change in momentum happens...

The bigger the force causing the change must be

36

Define stopping distance of a vehicle

The distance covered between the driver first spotting a hazard and the vehicle coming to a complete stop

37

Formula for stopping distance

Thinking distance + braking distance

38

Define thinking distance

The distance the car travels in the driver's reaction time

39

Two main factors that affects thinking distance

-Reaction time: this is increased by tiredness, alcohol, drugs and distractions
-Speed: the faster you're going, the further you'll travel during your reaction time

40

Define braking distance

The distance taken to stop once the brakes have been applied

41

Factors affected by the braking distance

-Speed: the faster you're going, the longer it takes to stop
-Mass: a car full of people and luggage won't stop as quickly as an empty car
-Condition of the brakes: Worn of faulty brakes won't be able to brake with as much force
-Friction between the tyres and the road: you're more likely to skid if the road is dirty, if it's icy or wet or if the tyres are bald

42

State the 2 things that can be done with energy

Transferred or helping in different energy stores

43

Define kinetic energy

Movement of an object

44

Define thermal energy

Heat. The hotter it is, the more energy it has in this store

45

Define chemical energy

Anything that can release energy via a chemicals reaction

46

Define gravitational potential energy

Anything in a gravitational field (i.e. anything that can fall)

47

Define elastic potential energy

Anything that is stretched

48

Define electrostatic energy

Two electric charges that attract or repel each other

49

Define magnetic energy

Two magnetic fields that attract or repel each other

50

Define nuclear energy

Atomic nuclei release energy from this store in nuclear reactions

51

Formula for kinetic energy

0.5 x mass x speed^2

52

Formula for gravitational potential energy

Change in gravitational energy = mass x gravitational field strength x change in vertical height

53

Define conservation energy

Energy is never created or destroyed

54

State what a closed system of energy is

A system (collection of objects) that can be treated completely on its own, without any energy being exchanged to or from the surroundings. It's not closed if the energy increases or decreases

55

State the four main ways that energy can be stored

-Mechanically
-Electrically
-By heating
-By radiation

56

Explain how energy can be stored mechanically

By a force acting on an object e.g. pushing and pulling

57

Explain how energy can be stored electrically

By a charge doing work e.g. charges moving round a circuit

58

Explain how energy can be stored by heating

Energy transferred from a hotter object to a colder object e.g. heating a pan on a hob

59

Explain how energy can be stored by radiation

Energy transferred by waves e.g. energy from the sun reaching earth by light

60

Energy is only useful when it is...

Transferred from one store to a useful store

61

Formula for total energy input

Total energy input = useful energy output + wasted energy

62

The less energy that's wasted...

The more efficient the device is said to be

63

Formula for energy efficiency

Efficiency = useful energy / total x 100%

64

State the name of the diagram that divides useful and wasted energy

Sankey diagram

65

Explain how a sankey diagram is presented

- A horizontal arrow represents useful energy
-Wasted energy splits off vertically downwards
-Thickness of the arrows represents the energy

66

State the two ways that can reduce unwanted energy transfers

Friction and lubrication

67

Explain how lubrication reduces energy transferred by friction

Lubricants can be used to reduce the friction between the objects' surfaces when they move.
They are usually liquids, so they can flow easily between objects and coat them

68

Explain how insulation reduced unwanted energy transfer by heating

Surround the object with something that will shield the thermal energy from escaping

69

Define conduction

The process by which heat is directly transmitted through the material of a substance when there is a difference of temperature between adjoining regions, without movement of the material

70

Define thermal conductivity

It describes how well a material transfers energy by conduction. For example, metals have a high thermal conductivity and gases have a low thermal conductivity

71

Define non-renewable energy resources

They are energy resources (such as fossil fuels and nuclear fuel) that will eventually run out

72

Define fossil fuel

Natural resources that form underground over millions of years that are typically burnt to provide energy

73

State the advantages of non-renewable energy resources

-They are reliable
-It's easy to meet a change in demand
-The cost to extract fossil fuels and build fossil fuel power plants are cheap

74

Disadvantages of using non-renewable energy resources

-Fossil fuels are slowly running out
-They create environmental problems:
-Fossil fuels release carbon dioxide which adds to the greenhouse effect
-Burning coal and oil can release sulphur dioxide which causes acid rain
-Oil spillages can harm animals
-Nuclear waste is very dangerous and difficult to dispose of

75

Define renewable energy resources

Energy resources that will never run out

76

Advantages of renewable energy resources

-They will never run out
-Damage much less harmful than non-renewable

77

State the disadvantages of renewable energy resources

-They don't provide much energy
-They are unreliable because they depend on the weather

78

Renewable energy resources include...

Bio-fuels, wind, the sun, hydro-electricity, tides

79

Define bio-fuels

Renewable energy resources created from either plant products or animal dung

80

Advantages of bio-fuels

-Supposedly carbon neutral
-Reliable

81

Disadvantages of bio-fuels

-Can't respond to immediate energy demands
-Cost to refine them are high
-Causes deforestation

82

Define wind power

Electricity from wind. Produced by wind turbines

83

Advantages of wind turbines

-No pollution
-Renewable
-Running costs are low

84

Disadvantages of wind turbines

-Initial costs are high
-Lots are needed to produce sufficient power
-Can spoil the view
-Can be noisy
-Relies on it being windy

85

Define solar cells

Made from materials that use energy transferred by light to create an electric current

86

Advantages of solar cells

-No pollution
-No running costs

87

Disadvantages of solar cells

-High initial costs
-Can't be produced at night

88

Define hydro-electricity

It involves flooding a valley and building a big dam. Rainwater is caught and allowed out through turbines

89

Advantages in hydro-electricity

-No pollution
-It can immediately respond to increased electricity demand
-Minimal running costs
-Reliable

90

Disadvantages of hydro-electricity

-Big impact on the environment (due to flooding of the valley and loss of habitat)
-High initial costs

91

Define tidal barrages

Big dams built across river estuaries with turbines in them. As the tide comes in it fills up the estuary. The water is then let out through turbines at a controlled speed to generate electricity

92

Advantages of tidal barrages

-No pollution
-Reliable
-No fuel costs
-Minimal running costs

93

Disadvantages of tidal barrages

-Can affect boat access
-Can affect the view
-Can affect wildlife
-They don't work when the water is level either side
-Moderately high initial costs