Motion, Forces And Conservation Of Energy Flashcards
1
Q
Vector
A
Have a magnitude and a direction
2
Q
Example of vector
A
Force
Velocity
Displacement
3
Q
Scalar
A
Only have a magnitude
4
Q
Example of scalar
A
Speed
Distance
Mass
Energy
5
Q
Distance
Scalar or vector and why
A
It is just how far an object has moved
Scalar
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
7
Q
Speed scalar or vector
A
How fast you’re going with no regard to direction
- scalar
8
Q
Velocity
Scalar or vector and why
A
Is speed in a given direction - vector
9
Q
Distance equation
A
Distance = speed x time
10
Q
Acceleration
A
Is the change of velocity in a certain amount of time
11
Q
The average acceleration equation
A
Acceleration =(final velocity - initial velocity)/ time
12
Q
Uniform acceleration
A
Mean a constant acceleration
Acceleration due to gravity for objects in free fall - 10m/s squared
13
Q
Uniform acceleration equation
A
Final velocity 2 - initial velocity2 = 2 x acceleration x distance
2 mean squared
14
Q
What does the gradient of a distance/time graph describe?
A
Gives the speed of the object at any given point
15
Q
What do the flat sections of a distance/time graph describe?
A
It means that the object has stopped
16
Q
What does a steeper distance/time graph mean?
A
It’s going faster
17
Q
What do the curves of a distance/time graph describe?
A
They represent acceleration
18
Q
What does a curve getting steeper mean on a distance/time graph?
A
Means it’s speeding up
19
Q
What does a levelling off curve mean on a distance/time graph?
A
Means it’s slowing down
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
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.
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
23
Q
What does the gradient describe in a velocity/time graph?
A
Acceleration
24
Q
What do the flat sections of a velocity/time graph describe?
A
Represent a steady speed
25
What does it mean if a velocity/time graph is steep?
The greater the deceleration or acceleration
26
What do the uphill sections mean on a velocity/time graph?
Acceleration
27
What do the downhill sections of a velocity/time graph mean?
Deceleration
28
What does a curve mean on a velocity/time graph?
A change of acceleration
29
How do you calculate the distance travelled in a velocity/time graph?
The area under any section of the graph
| You have to calculate the area
30
Newton’s first law
To make an object speed up or slow down or start a stationary object moving, a force needs to be applied
31
If a resultant force = 0
The object is stationary or at a constant speed
32
Of a resultant force does not equal 0
The speed or direction of the objects changes
33
What is the resultant force equation?
Resultant force = mass x acceleration
34
Why are large deceleration dangerous?
Because a large deceleration requires a large force
35
What are some safety features in vehicles and what are they supposed to do?
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
36
What are crumple zones?
Are areas at the front and back of a vehicle which crumple up easily in a collision, increasing the time taken to stop.
37
How do brakes on a vehicle work?
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
38
Inertia
The tendency for motion to remain unchanged
| Ratio of force over acceleration
39
What is Newton’s third law?
When two objects interact, the forces they exert on each other are equal and opposite
40
Momentum equation
Momentum = mass x velocity
41
Force and momentum equation
Force = change in momentum
| Time
42
What is stopping distance?
Thinking distance + braking distance
43
Thinking distance
The distance travelled whilst a driver reacts and presses the brake pedal
44
Braking distance
The distance travelled when the brake pedal is pressed until the car stops
45
What effects your thinking distance / reaction time?
```
Caffeine
Alcohol
Drugs
Distractions
Tiredness
```
46
What effects braking distance?
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Road surface
Speed
Tyre quality
Mass of car
Weather
Brakes
Friction between tyre and road
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47
Contact forces
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Drag
Friction
Normal
Thrust
Tension
```
48
Non contact forces
Weight
Magnetic
Electric
49
Conduction
When heat is applied to the metal rod the particles start to vibrate and pass the heat through the metal rod.
50
Convection
Only happens in gas and liquids
51
Kinetic energy equation
Kinetic energy = 0.5 x mass x (speed)2
52
Gravitational potential energy store
Gravitational potential = mass x gravity field x change in height
53
Energy efficiency equation
Efficiency = useful energy transferred
Total energy used
X100 to get a percentage
54
Why is heat loss bad?
Costs money
Not good for the environment
Need more energy
55
How to reduce heat loss-lubrication
Reduces friction which not only reduces heat loss but also reduces wear and tear on moving parts
56
Insulation reduces heat loss
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
How to reduce heat loss-low residence wires
The higher the wire resistance the less heat loss through the current heating effect
58
Non renewable resources - fossil fuels
Reliable
Low cost to extract
Power plants are cheap to build
Slowly running out
59
Non renewable resources - nuclear energy
Reliable
They are costly to build and to safely decommission
Clean energy but the waste is very dangerous
60
Environmental problems of fossil fuels
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
Environmental impacts of Nuclear energy
Risk of major catastrophe like the Fukushima disaster
| Very dangerous and difficult to dispose of
62
Advantages of nuclear fuels
Very reliable
| No carbon dioxide released when burned
63
Disadvantages of nuclear fuel
Targets for terrorists
If in seas - kills animals
Use concrete to make a power station - releases carbon dioxide
64
Bio fuels
Renewable energy resources created from either plant products or animal dung. They are burnt to produce electricity or run cars
65
Advantages of biofuels
Fairly reliable
| Crops take a relatively short time to grow and different crops can be grown all year
66
Disadvantages of biofuels
They cannot reindeer to immediate energy demands
Expensive
In some areas - forest has been cut down to make room to grow biofuels
67
Why might figures of how much non renewable sources change from different sources?
Might speed up or slow down how fast we use them
More reserves may be found
World population may change
68
Wind power
Wind rotates the blades which turn the generator- produces electricity
Initial costs are high
Noisy - spoil the view
Only work when windy
69
Wind power disadvantages
Initial costs are high
Noisy - spoil the view
Only work when windy
70
Solar panels
Solar panels are made form materials that use energy transferred by light to create an electric current
71
Solar panel advantages
No pollution
| No running costs
72
Disadvantages of solar panels
Generate relatively small scale - homes
Most suitable for sunny countries
Can’t make solar power at night
73
Hydroelectricity
Usually involves flooding a valley by building a big dam
| Rainwater is caught and allowed out by turbines
74
Disadvantages of hydro electricity
Flooding can cause loss of habitat
| Initial costs are high
75
Advantages of hydro electricity
It can immediately respond to high electricity demand
Minimal running costs
Reliable energy resource
76
Walking speed
1.4 m/s
| 5 km/h
76
Running speed
3m/s
| 11km/s
76
Cycling speed
5.5m/s
| 20km/h
76
Cars in built up area
13m/s
| 47km/h
76
Cars on motorway
31m/s
| 112km/h
77
Trains speed
55m/s
| 200km/h
78
Aeroplane speed
250m/s
| 900km/h
79
Ferries speed
15m/s
| 54km/h
80
Wind speed
5-20 m/s
81
Speed of sound in air
340 m/s
82
What is weight?
The force action on an object due to gravity - measure in Newton’s
83
Weight equation
Weight =mass x gravitational field strength
84
How is weight measured?
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
Circular motion
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
Newton’s second law
Force = (change in momentum) / time
87
Conservation of energy
Energy can be stored, transferred between stores and dissipated but I can never be created or destroyed
88
What is a closed system?
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
An object rolling up a slope
Works against the gravitational force, energy is transferred mechanically from the kinetic energy store of the ball to its gpe store
90
A bat hitting a ball
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
A rock dropping from a cliff
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
A car slowing down without breaking
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
A kettle boiling water
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
Parts of energy transfer diagrams
Boxes - energy stores
| Arrows - transfers
95
Mechanically - energy transfer
A force acting on an object - pushing stretching squashing
96
Electrically - energy transfers
A charge doing work - charges moving around a circuit
97
By heating - energy transfers
Energy transferred from a hotter object to a colder object - heating a pan on a hob
98
By radiation - energy transfers
Energy transferred by waves - energy from the sun reaching earth by light
99
Wasted energy - mechanically
Mechanical processes become wasteful when they cause a rise in temperature so dissipating energy in heating surroundings
100
Electrically transferred - wasted energy
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
Conservation of energy principle
Total energy input = useful energy output + wasteful energy
102
Snakes diagrams
Big arrow =useful energy
Little arrow =wasted energy
Arrow = total energy input
103
What is the effect of the thickness and thermal conductivity of the walls
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
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 let out by turbines to generate electricity
105
Advantages of tidal barrages
No pollution
Tides are pretty reliable
No fuel costs and minimal running costs
106
Disadvantages of tidal barrages
```
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
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107
What are the trends in energy resources currently?
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
What industries are going it be affects by the energy change?
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
What are the disadvantages of the targets to change to renewable energy?
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.
