Topic 1- Motion, Forces And Conservation Of Energy Flashcards Preview

Physics > Topic 1- Motion, Forces And Conservation Of Energy > Flashcards

Flashcards in Topic 1- Motion, Forces And Conservation Of Energy Deck (49):
1

8 Energy stores

Kinetic, Thermal, Chemical, Nuclear, Magnetic, Electrostatic, Elastic Potential, GPE

2

Kenton energy depends on...

Mass and speed
Greater the mass and the faster it’s going, the more kinetic energy

3

If you double the mass, the energy in the kinetic energy store...

Doubles

4

If you double the speed, the energy in the kinetic energy store...

Quadruples

5

Energy can be ... , ... between stores and ...
But can never be ... or ...
The total energy of a closed system has...

Stored, transferred and dissipated
Can never be created or destroyed
No net charge

6

Energy can be transferred between stores in four main ways...

Mechanically
Electrically
By heating
By radiation

7

A ball rolling up a slope

The ball does work against the gravitational force
So energy is transferred mechanically from the mentor energy store of the ball to its gravitational potential energy store

8

A bat hitting a ball

Bat has energy in its kinetic energy store
Some out this is transferred mechanically to the balls kinetic energy store
Some is also transferred mechanically to the thermal energy stores of the bat, ball and surroundings
The rest is carried away by sound

9

Energy is only useful when...

It is transferred from one store to a useful store

10

Input energy is always ... and ... to the surroundings

Dissipated or wasted
Often to thermal energy stores

11

When work is done mechanically ... have to be overcome eg.
Therefore...

Frictional forces eg. Things rubbing together and air resistance
Therefore energy needed to overcome this is transferred to thermal energy stores (not useful energy)

12

What reduces unwanted energy transfers

Lubricants- reduce friction between objects when they move usually liquids like oil, can flow easily between objects and coat them
Insulation- between walls of houses, lowest conductivity means slowest rate of energy transferred through them (thick walls and a air gap between the two walls)

13

Non renewable advantages

Reliable- can meet the current demand, use more fuel to release more energy
Cheap to build and run fossil fuel power plants
Low cost of extracting fossil fuels

14

Disadvantages of non renewable

Nuclear power plants cost a lot to build and cause safety issues
Slowly running out
Environmental problems, contribute to global warming
Cause acid rain
Oil spillages
Nuclear waste is dangerous

15

Renewable advantages

Never run out
Not as much impact on environment

16

Disadvantages of renewable

Don’t provide much energy
Not efficient
Weather dependant

17

Biofuels

Made from plants and waste
Can not respond to immediate energy demands
Cost lots
Increases methane and carbon dioxide emissions
Reliable because crops grow quickly

18

Wind power

Initial costs are high but minimal to run
No pollution
Lots of them are needed to produce lots of power
Spoil the view
Noisy
Only work when wind so can’t always supply to high demand

19

Solar cells

No pollution
Initial costs are high but minimal to run
Generate small scale electricity
Most suitable for sunny countries
No power made at night
Can’t increase production when there is extra demand

20

Hydro-electricity

No pollution
Big impact on environment due to flooding possible loss of housings or habitats
Immediately respond to increased electricity demand
Initial costs are high but minimal running cost
Generally reliable

21

Tidal barrages

No pollution
Effect boat access
Can spoil view
Alter wildlife
Reliable
Don’t work when water levels are equal both sides
Initial costs are high but minimal running costs
No fuel costs

22

Vectors...

Have a magnitude (size) and direction

23

Vector quantities

Force
Velocity
Displacement
Weight
Acceleration
Momentum

24

Scalar

Only have a magnitude and no direction

25

Scalar quantities

Speed
Distance
Mass
Energy
Temperature
Time

26

Speed is...

Just how fast something is travelling with no regard to direction

27

Velocity is ...

Speed in a given direction

28

Distance is...

How far an object has moved

29

Displacement is ...

A measurement of direction and distance in a straight line from a starting point to its finishing point

30

Acceleration is ...

The change in velocity in a certain amount of time

31

Deceleration is ...

Negative acceleration

32

Constant acceleration can also be called

Uniform acceleration

33

Example of uniform acceleration

Acceleration due to gravity

34

Acceleration equation

a = (v-u) / t

35

Uniform acceleration equation

(v)2 - (u)2 = 2 x a x X

The 2s around the brackets = squared
The small x = multiply
Large X = distance

36

Distance- speed graph :
What does the gradient mean
Flat sections
Curves

Gradient at any point gives the speed
Flat sections is where the object has stopped
Curves are represent acceleration, the steeper the curve the greater the acceleration and if the curve sloops off the slower the acceleration

37

Finding speed from a distance - time graph

The gradient = speed

38

Velocity- time graphs :
Gradient
Flat sections
Up
Down
Curve

Gradient = acceleration
Flat sections = steady speed
Up = acceleration
Down = deceleration
Curve = changing acceleration

39

How to get distance from a velocity- time graph

The area underneath the graph is the distance travelled

40

Momentum is ...

A property that all moving objects have. Defined as a product of an objects mass and velocity
Vector quantity - has size and direction

41

Greater mass or velocity
Affect on momentum

Increases
More momentum

42

Total momentum before = ?

Total momentum after

43

What is conservative of momentum

The momentum being the same before and after an event

44

Newton’s first law

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

45

A non zero resultant force will ...

Always produce acceleration or deceleration in the direction of the force

46

Acceleration is proportional to...
therefore...

Resultant force
Therefore the more an object accelerates the larger the resultant force

47

Newton’s second law

Resultant force = mass x acceleration

49

Acceleration is inversely proportional to...
therefore...

The mass of the object
Therefore the larger the mass, the slower the acceleration

50

Safety features are designed to..
For example..

Increase collision times to reduce risk of injury
Seat belts, air bags, crumple zones ( at front and back of vehicles)