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Flashcards in Clockwork Universe Deck (69):
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?

Less then 1x10^-9

66

Whats the wavelength of UV

1x10^-9 to 4x10^-7

67

Whats the wavelength of visible light?

4x10^-7 to 8x10^-7

68

Whats the wavelength of Infra red?

8x10^-7 to 1x10^-3

69

Whats the wavelength of Microwaves

Greater then 1x10^-3