Flashcards in Clockwork Universe Deck (86):

1

## How can you calculate the acceleration during SHM when given only displacement and frequency?

###
A=w^2 x

W= 2pi f

2

## What happens to displacement and acceleration of a body during SHM when velocity is max?

###
Displacement = 0

Acceleration =0

3

## What happens to he amplitude when the driving frequency is equal to the natural frequency?

### Amplitude is Max

4

## How can you work out power lost in transmission?

### P= I^2 R

5

## How can you find the energy of a particle?

### E=KT

6

## If 2 gasses with atoms of different masses where exposed to the same temperature and pressure. What would happen to their KE

###
KE is the same as:

KE = KT

However there Velocity’s would be different

7

## How can you find the force exerted by a gas on an object?

###
F=PA

Assuming collisions are elastic

8

## When discussing semi conductors, what is the Band Gap?

### The band gap is the energy difference between the conduction band and the valency band. Electrons in the conduction band are free to conduct throughout the semiconductor structure. Electrons in the valency band are bound and are not able to conduct.

9

## How can equipotentials show field strength falls

### Density of lines decreases/line spacing increases, and equipotentials have equal potential between them

10

## How is acceleration related to displacement during SHM

### Acceleration is directly proportional to the negative of displacement

11

## How can you find the distance using an echo?

### 0.5*v*t

12

## How can the number of gas monocles be worked out?

###
PV = NkT = nRT

Where N is the number of atoms, n is the number of moles, and T is the temperature in kelvin

13

## How can a graph of discharge (charge-time) be used to find resistance?

###
Rearrange Q=Q0 e^(t/rc)

Pick a point in the graph and put in the equation

14

## How can you see if a value is exponential

###
Find the ratios of adjacent values of change of other value is the same e.g.

273 530

298 920

323 1550

530/920 = 0.58

920/1550 = 0.61

15

## In Boltzmann equations, what is the value ɛ?

### ɛ is the activation energy, in joules per particle or its the work function solar cells

16

## Show that GPE is given by -Gmm/r

###
Potential (Vg) = -GM/R

Potential Energy (E) = mVg

Potential Energy = -GMm/R

17

## In which direction is the resultant on a satellite

### Towards the centre/planet/inwards

18

## What happens to wavelength during redshift

### It increases

19

## In which direction is GPE

### Always negative

20

## How can root mean squared be calculated when given molar mass and average particle energy

### V=(2E/M)^0.5

21

## What is the meant by the term random walk of gas monocles, and what is its cause

###
Random walk is when a monocle takes a path of a series of straight lines varying in length and direction

Its caused by the ransom collision of molecules, and it causes random change in direction and velocity

22

## What is the unit for root mean square

### ms-1

23

## How does red shift prove the big bang

###
Universe is expanding, so galaxies are moving apart at an increasing speed (rate of expansion is rising)

This means at one point they were all together

24

## How can gas in a box act as a spring?

###
As volume decreases pressure increases, meaning there are more collisions

The gasses transfer more momentum to the outside of the box, and the force of the collisions causes the box to return to its original position

25

## What is an ideal gas

###
The particles occupy a negligible amount of the total volume

There is no attraction between particles

All collisions are elastic

26

## How can you work out the velocity of the particles from a rockets exhaust gases used to slow it down

###
Work out the change in momentum

Work out the Mass of the gas lost

Work out velocity using P=MV

27

## How does energy stored in a resistor change as V increases

### It increases with an increasing gradient

28

## What the unit for gravitational potential

### J kg-1

29

## How can work done by friction be calculated

### Work done = GPE - KE

30

## In the Boltzmann factor. What does KT refer to?

### Average thermal energy

31

## Sketch 3 equipotentials around a large mass separated by the same Potential Difference

### Equipotentials of Increasing distance between them

32

## How can the change in KE be calculated when a mass of airs temperature is changed

###
E=NkT

Where N is the number of particles

33

## Why would a spring need dampened

###
May vibrate at natural frequency

Causing resonance leading to max amplitude

Dampening reduces energy, dissipating it as heat, reducing amplitude

34

## What is the equation for centripetal force

### F = mv^2/r

35

## Why are some wavelengths and not others of light absorbed by hydrogen gas during absorption light spectrum

### The energies of these wavelengths are equal to the differences in electron energy levels of the hydrogen, so they are emitted in every direction

36

## How can Gravitational field strength (g) and Gravitational Potential (V) be calculated from a Potential - distance graph Graph

###
g = v/r = gradient

v = g*r = Area

37

## How can work done by a moving mass (or charge) between 2 points on a field strength - distance graph

### multiply the area under the graph by the mass or charge

38

## How are gravitational field strength and Radius from the centre related when inside of the earth

### G is directly proportional to r

39

## How can you deduce an equation to show that gravitational field strength is directly proportional to the radius

###
g = gm/r^2

P = M/v

= M/(4/3)π r^3

m = (4/3) P π r^3

g = (4/3) P π r^3 / r^2

g = (4/3) P π r

40

## Why is gravitational field strength 0 in the centre of the earth

### Its being pulled in every direction equal amounts

41

## How can you describe the charge across 2 plates of a resistor

### Equal and Opposite

42

## Define Gravitational Potential

### the work done to move an object from infinity to a point in space

43

## What is Newtons 3rd law and how does it related to an object sitting on the ground

### Every action has an equal and opposite reaction. e.g if an object it sitting at rest on the downwards gravitational force of the earth on the object is equal to the upwards gravitational force of the object on the earth

44

## When 2 objects collide, what is the total change in momentum of both objects

### No change in momentum, momentum must be conserved

45

## How does field strength vary between a positive and negative plate, and how can it be calculated

###
Field strength is constant at every point.

It can be calculated by E=V/d

46

## Which neutrino is paired with which particle during radio active decay

###
Neutrino - Positron

Anti Neutrino - Electron

47

## What is the definition of SHM

###
Acceleration Always act towards the centre of motion

Acceleration is Directly proportional to the displacement (negative)

48

## What is the equation for velocity during SHM in terms of w, A, and x

### V= w(A^2-x^2)^0.5

49

## How can you calculate maximum values for SHM

### Use the Sin and Cos equations from the formula sheet, and see when sin and cos = 1

50

## What the equations for Energies in SHM

###
KE = 1/2 * m * (wA)^2

PE = KEmax - KE

= 1/2 * m * w^2 * x^2

51

## What are the units for Energy

###
Kg m^2 s^-2

Nm

Joule

Watt Hour

52

## How does amplitude of a spring vary as frequency is increased to and past the resonance

###
Increases with increasing gradient

Peaks ar resonance

then falls with decreasing gradient to below starting point

53

## Describe the gravitational force of an object moving from a planet to its moon

### Begins strong and negative, falls with decreasing gradient, passes through 0, becomes positive (force direction change) then increases with an increasing gradient

54

## How to calculate Root Mean Square speed of particles in a gas

###
Pv = 1/3 Nm (M.S)

Becares to root M.S as thats average velocity squared

55

## Calculate pressure of a gas if given only mass per monocle, and volume

###
p = Nm/v

where N is the number of particles

56

## Why does gravitational force not effect the speed of a satellite

### force at right angles to velocity/motion so no work done/energy transferred

57

## Why is the age of the universe likely greater then that calculated by 1/Ho

### Unvertnelty In value as distance between galaxies if difficult to measure, universe didn't begin as galaxies, Non-linear expansion

58

## How does GPE vary with time of an object falling freely from the ground

###
Starts at a fixed Y intercept

Falls to the ground with an increasing gradient

Reaches 0 after certain time

59

## How could an astronomer use the wavelength of a radar echo to measure the velocity of an object moving though space

###
Measure the change in wavelength from emission to reflection

Δλ/λ = V/C

60

## What is the velocity vector on an orbiting object and how is it drawn

### Drawn as a tangent to the path of orbit

61

## How can you work out velocities of an object in an elliptical orbit at different distances from the earth

###
E Total = E grav + E Kinetic

E total is constant throughout the orbit, E grav can be calculated, and those values can be used to find kinetic E and therefore V

62

## How does energy on a capacitor vary with charge across plates

### Y=X^2 relationship

63

## Explain how a monocle that can move a distance of 5mm in one second takes 100s to be displaced 50mm

###
Distance = k No.Collisions^0.5

No.Collisions = c t

Therefore

t = distance/time^0.5

64

## What is the Nuclear Density Constant and how is it found

###
If you plot the radius of a nucleus against the cube root of its mass number, the graph would have the equation:

R=Ro A^1/3

Where Ro is the radius of a single nucleon

Assuming the nucleus is a sphere, using this and the equation density = mass/volume:

p = 3m / 4πRo^3

65

## Whats the wavelength of X-rays?

### 10^-9

66

## Whats the wavelength of UV

### 10^-8

67

## Whats the wavelength of visible light?

### 10^-7

68

## Whats the wavelength of Infra red?

### 10^-6

69

## Whats the wavelength of Microwaves

### 10^-2

70

## What does a graph go the Boltzmann factor look like

###
Starts at 0

Rapid increase in Gradient until e/k

After that the gradient reduces to constant and shallow

71

## In a space time diagram why are worked lines 45 degrees?

### Travels 1 Light second in one second

72

## In an iterative model how can you air resistance has been ignored

### The equation used doesn't factor in a drag/resistive force

73

## Why are iterative models useful

###
Some problems can only be modelled iteratively

Models can be improved with real world data

74

## How can you find the total energy of an object in orbit

###
Potential energy + kinetic energy

Remember Potential Energy is always negative and a vector

75

## How does velocity vary with force during SHM

###
λ/4 behind

Opposite/Negative

ie if force is sin, velocity is -cos

76

## How can you find the change in pressure of a gas, if its particles have been replaced with ones of a new mass but unchanged density volume and temperature

###
Find the new number of particles by comparing masses and multiplying by old number

then us PV=NKT

77

## How can you find work done to reduce an objects radius

### Work = Ek+Egrav

78

## How can you find potential from a field strength distance graph

### Find the area from d-infintity

79

## Whats the equation for current in a component to charge stored by a capacitor

### I = -dQ/dt

80

## What are the graphs for e^e/kt and e^-e/kt

###
e^-e/kt: Starts at origon, rapid increase, then plates to a steady increase at e/t

e^e/kt: Starts at max then falls, same as negative exponential

81

## How can you find the pressure on onside of a wall if its supporting a wall

###
Pressure difference = f/a

Pressure on Side = Pressure on other side - Difference

82

## Why is kinetic energy required for an atom to leave a gravitational field given by Ek=Gmm/r

###
GPE = -Gmm/r

KE+GPE must be grater then 0 for escape (remember GPE is negative)

83

## How can you work out the velocity of a string if given its amplitude and frequency

###
v=wr

w=2πf

84

## Whats newtons first and second law of motion

###
1: object at rest stays at rest or with the same speed unless acted upon by a force

2: The acceleration of an object is dependent upon two variables - the net force and the mass of the object.

85

## How can you find the change of a metal sphere given voltage

### v=kq/r

86