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Physics Daisy > Motion, Forces And Conservation Of Energy > Flashcards

Motion, Forces And Conservation Of Energy Flashcards

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1
Q

Vector

A

Have a magnitude and a direction

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2
Q

Example of vector

A

Force
Velocity
Displacement

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3
Q

Scalar

A

Only have a magnitude

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4
Q

Example of scalar

A

Speed
Distance
Mass
Energy

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5
Q

Distance

Scalar or vector and why

A

It is just how far an object has moved

Scalar

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6
Q

Displacement

Scalar or vector and why?

A

Measures the distance and direction in a straight line from an objects starting point to an objects finishing point

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7
Q

Speed scalar or vector

A

How fast you’re going with no regard to direction

- scalar

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8
Q

Velocity

Scalar or vector and why

A

Is speed in a given direction - vector

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9
Q

Distance equation

A

Distance = speed x time

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10
Q

Acceleration

A

Is the change of velocity in a certain amount of time

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11
Q

The average acceleration equation

A

Acceleration =(final velocity - initial velocity)/ time

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12
Q

Uniform acceleration

A

Mean a constant acceleration

Acceleration due to gravity for objects in free fall - 10m/s squared

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13
Q

Uniform acceleration equation

A

Final velocity 2 - initial velocity2 = 2 x acceleration x distance

2 mean squared

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14
Q

What does the gradient of a distance/time graph describe?

A

Gives the speed of the object at any given point

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15
Q

What do the flat sections of a distance/time graph describe?

A

It means that the object has stopped

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16
Q

What does a steeper distance/time graph mean?

A

It’s going faster

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17
Q

What do the curves of a distance/time graph describe?

A

They represent acceleration

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18
Q

What does a curve getting steeper mean on a distance/time graph?

A

Means it’s speeding up

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19
Q

What does a levelling off curve mean on a distance/time graph?

A

Means it’s slowing down

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20
Q

How can you calculate the speed at a point along the line on a distance/time graph?

A

Speed = gradient = change in vertical

Change in horizontal

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21
Q

How do you calculate the speed on a distance/time graph if the line is curved?

A

You need a draw a tangent to the curve at that point, and then find the gradient of the tangent.

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22
Q

How do you calculate the average speed on a distance/time graph?

A

Divide the total distance travelled by the time it takes

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23
Q

What does the gradient describe in a velocity/time graph?

A

Acceleration

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24
Q

What do the flat sections of a velocity/time graph describe?

A

Represent a steady speed

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25
Q

What does it mean if a velocity/time graph is steep?

A

The greater the deceleration or acceleration

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26
Q

What do the uphill sections mean on a velocity/time graph?

A

Acceleration

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27
Q

What do the downhill sections of a velocity/time graph mean?

A

Deceleration

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28
Q

What does a curve mean on a velocity/time graph?

A

A change of acceleration

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29
Q

How do you calculate the distance travelled in a velocity/time graph?

A

The area under any section of the graph

You have to calculate the area

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30
Q

Newton’s first law

A

To make an object speed up or slow down or start a stationary object moving, a force needs to be applied

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31
Q

If a resultant force = 0

A

The object is stationary or at a constant speed

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32
Q

Of a resultant force does not equal 0

A

The speed or direction of the objects changes

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33
Q

What is the resultant force equation?

A

Resultant force = mass x acceleration

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34
Q

Why are large deceleration dangerous?

A

Because a large deceleration requires a large force

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35
Q

What are some safety features in vehicles and what are they supposed to do?

A

They are designed to increase collision times which reduces the force which reduces chance of injury
Seatbelt stretch slightly
Air bags slow you down gradually

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36
Q

What are crumple zones?

A

Are areas at the front and back of a vehicle which crumple up easily in a collision, increasing the time taken to stop.

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37
Q

How do brakes on a vehicle work?

A

The brakes of a vehicle do work on its wheels. This transfers energy from the vehicles kinetic energy store to the thermal energy store of the brakes

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38
Q

Inertia

A

The tendency for motion to remain unchanged

Ratio of force over acceleration

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39
Q

What is Newton’s third law?

A

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

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40
Q

Momentum equation

A

Momentum = mass x velocity

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41
Q

Force and momentum equation

A

Force = change in momentum

Time

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42
Q

What is stopping distance?

A

Thinking distance + braking distance

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43
Q

Thinking distance

A

The distance travelled whilst a driver reacts and presses the brake pedal

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44
Q

Braking distance

A

The distance travelled when the brake pedal is pressed until the car stops

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45
Q

What effects your thinking distance / reaction time?

A 
Caffeine 
Alcohol 
Drugs 
Distractions 
Tiredness
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46
Q

What effects braking distance?

A 
Road surface 
Speed 
Tyre quality 
Mass of car 
Weather 
Brakes 
Friction between tyre and road
47
Q

Contact forces

A 
Drag 
Friction 
Normal 
Thrust 
Tension
48
Q

Non contact forces

A

Weight
Magnetic
Electric

49
Q

Conduction

A

When heat is applied to the metal rod the particles start to vibrate and pass the heat through the metal rod.

50
Q

Convection

A

Only happens in gas and liquids

51
Q

Kinetic energy equation

A

Kinetic energy = 0.5 x mass x (speed)2

52
Q

Gravitational potential energy store

A

Gravitational potential = mass x gravity field x change in height

53
Q

Energy efficiency equation

A

Efficiency = useful energy transferred
Total energy used
X100 to get a percentage

54
Q

Why is heat loss bad?

A

Costs money
Not good for the environment
Need more energy

55
Q

How to reduce heat loss-lubrication

A

Reduces friction which not only reduces heat loss but also reduces wear and tear on moving parts

56
Q

Insulation reduces heat loss

A

One side of an object is heated , particles in the hotter part vibrate more and collide with each other. This transfers heat energy stores to other particles

57
Q

How to reduce heat loss-low residence wires

A

The higher the wire resistance the less heat loss through the current heating effect

58
Q

Non renewable resources - fossil fuels

A

Reliable
Low cost to extract
Power plants are cheap to build
Slowly running out

59
Q

Non renewable resources - nuclear energy

A

Reliable
They are costly to build and to safely decommission
Clean energy but the waste is very dangerous

60
Q

Environmental problems of fossil fuels

A

Release carbon dioxide into the atmosphere when burned
Contributes to global warming
Burning oil and coals sulfur dioxide -acid rain
Oil spillages - kill animals

61
Q

Environmental impacts of Nuclear energy

A

Risk of major catastrophe like the Fukushima disaster

Very dangerous and difficult to dispose of

62
Q

Advantages of nuclear fuels

A

Very reliable

No carbon dioxide released when burned

63
Q

Disadvantages of nuclear fuel

A

Targets for terrorists
If in seas - kills animals
Use concrete to make a power station - releases carbon dioxide

64
Q

Bio fuels

A

Renewable energy resources created from either plant products or animal dung. They are burnt to produce electricity or run cars

65
Q

Advantages of biofuels

A

Fairly reliable

Crops take a relatively short time to grow and different crops can be grown all year

66
Q

Disadvantages of biofuels

A

They cannot reindeer to immediate energy demands
Expensive
In some areas - forest has been cut down to make room to grow biofuels

67
Q

Why might figures of how much non renewable sources change from different sources?

A

Might speed up or slow down how fast we use them
More reserves may be found
World population may change

68
Q

Wind power

A

Wind rotates the blades which turn the generator- produces electricity
Initial costs are high
Noisy - spoil the view
Only work when windy

69
Q

Wind power disadvantages

A

Initial costs are high
Noisy - spoil the view
Only work when windy

70
Q

Solar panels

A

Solar panels are made form materials that use energy transferred by light to create an electric current

71
Q

Solar panel advantages

A

No pollution

No running costs

72
Q

Disadvantages of solar panels

A

Generate relatively small scale - homes
Most suitable for sunny countries
Can’t make solar power at night

73
Q

Hydroelectricity

A

Usually involves flooding a valley by building a big dam

Rainwater is caught and allowed out by turbines

74
Q

Disadvantages of hydro electricity

A

Flooding can cause loss of habitat

Initial costs are high

75
Q

Advantages of hydro electricity

A

It can immediately respond to high electricity demand
Minimal running costs
Reliable energy resource

76
Q

Walking speed

A

1.4 m/s

5 km/h

76
Q

Running speed

A

3m/s

11km/s

76
Q

Cycling speed

A

5.5m/s

20km/h

76
Q

Cars in built up area

A

13m/s

47km/h

76
Q

Cars on motorway

A

31m/s

112km/h

77
Q

Trains speed

A

55m/s

200km/h

78
Q

Aeroplane speed

A

250m/s

900km/h

79
Q

Ferries speed

A

15m/s

54km/h

80
Q

Wind speed

A

5-20 m/s

81
Q

Speed of sound in air

A

340 m/s

82
Q

What is weight?

A

The force action on an object due to gravity - measure in Newton’s

83
Q

Weight equation

A

Weight =mass x gravitational field strength

84
Q

How is weight measured?

A

Using a calibrated spring board
Measure the force pulling the object to the centre of gravity
Spring balance will stretch until the force from spring is enough to balance the weight
The distance the spring has stretched shows the force it is exerting

85
Q

Circular motion

A

Objects travelling in a circle are constantly changing direction so it is changing velocity and therefore accelerating
Must be a resultant force that acts towards the centre
The force that keeps something moving in a circle is called centripetal force

86
Q

Newton’s second law

A

Force = (change in momentum) / time

87
Q

Conservation of energy

A

Energy can be stored, transferred between stores and dissipated but I can never be created or destroyed

88
Q

What is a closed system?

A

A system that can be treated completely on its own without any energy being exchange to or from its surroundings. Energy can’t increase or decrease
No net change to the total energy in that system

89
Q

An object rolling up a slope

A

Works against the gravitational force, energy is transferred mechanically from the kinetic energy store of the ball to its gpe store

90
Q

A bat hitting a ball

A

The bat has kinetic energy store. Some of it is transferred mechanically to the balls kinetic energy store. Some is mechanically transferred to the thermal energy stores of the bat and ball - the rest is carried away by sound

91
Q

A rock dropping from a cliff

A

Assuming their is no air resistance, gravity works on the rock , so it constantly accelerates towards the ground. Energy transfers mechanically from the rocks gpe store to its kinetic energy store

92
Q

A car slowing down without breaking

A

Energy in the kinetic energy store of the car is transferred mechanically -due to friction between the tyre and the road - and then by heating, to the thermal energy stores of the car and road.

93
Q

A kettle boiling water

A

Energy is transferred electrically from the mains to the heating element of the kettle and then by heating to the thermal energy store of the water.

94
Q

Parts of energy transfer diagrams

A

Boxes - energy stores

Arrows - transfers

95
Q

Mechanically - energy transfer

A

A force acting on an object - pushing stretching squashing

96
Q

Electrically - energy transfers

A

A charge doing work - charges moving around a circuit

97
Q

By heating - energy transfers

A

Energy transferred from a hotter object to a colder object - heating a pan on a hob

98
Q

By radiation - energy transfers

A

Energy transferred by waves - energy from the sun reaching earth by light

99
Q

Wasted energy - mechanically

A

Mechanical processes become wasteful when they cause a rise in temperature so dissipating energy in heating surroundings

100
Q

Electrically transferred - wasted energy

A

A motor transfers energy usefully from its kinetic energy store to the kinetic energy store and the gpe store of the load
Transfers energy mechanically to the thermal energy stores of its moving parts and electrically to the thermal energy stores of its moving parts
Energy is dissipated and surroundings are heated

101
Q

Conservation of energy principle

A

Total energy input = useful energy output + wasteful energy

102
Q

Snakes diagrams

A

Big arrow =useful energy
Little arrow =wasted energy
Arrow = total energy input

103
Q

What is the effect of the thickness and thermal conductivity of the walls

A

The lower the thermal conductivity of the wall the slower the rate of energy transfer through them - building will cool more slowly.
Some walls have cavity walls - an air gap in between them - slows down the amount of energy in-between them
The thicker the wall the slower the rate of energy transfer through them

104
Q

Tidal barrages

A

Big dams built across river estuaries with turbines in them

As the tide comes in it fills up the estuary - the water is let out by turbines to generate electricity

105
Q

Advantages of tidal barrages

A

No pollution
Tides are pretty reliable
No fuel costs and minimal running costs

106
Q

Disadvantages of tidal barrages

A 
Can affect boat access
 Spoils the view 
Alter habitats 
Doesn’t work if the sea level is the same height each side 
Initial costs are high
107
Q

What are the trends in energy resources currently?

A

Most electricity is produces by fossil fuels + nuclear power
Some electricity is from wind power
Fossil fuels used for vehicles and to heat homes
Aim is for renewable resources to provide for 15% of energy by 2020 in uk

108
Q

What industries are going it be affects by the energy change?

A

Pressure from other countries and public to make targets
Puts pressure on energy providers to build renewable power plants
Puts pressure on car companies - make electric and hybrid cars

109
Q

What are the disadvantages of the targets to change to renewable energy?

A

Cost money to build new power plants
Arguments on where to put new power plants
Some energy aren’t always reliable - combination of energy resources
Hybrid and electrical cars are expensive and so are solar panels.

Physics Daisy (11 decks)

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