The Universe And Its Physics

Question 1

Number of particles per m^3

Answer 1

Density/particle mass

Question 2

Newtons Laws

Answer 2

• no force = const momentum
• Force is proportional to change in momentum
• action = reaction

Question 3

Work done

Answer 3

F.r

F=gravitational force for large displacements

Question 4

Newton’s Shell Theorems

Answer 4

1. Gravitational force of a spherically symmetric mass can be calculated as if all the mass is a point mass in the centre
2. Gravitational force inside a shell = 0

Question 5

Flux and change in momentum equation including flux?

Answer 5

Particles per second through 1m^2 (brightness)
f=nv
Rate of change in momentum = Afmv = Intensity(Photon Energy)/c

F = L/(4pidistance^2)

Question 6

Radius of an electrons orbit?

Answer 6

Equate electric and centripetal force

Question 7

Wavelength of a photon emitted from energy level n1 - n2

Answer 7

= hc/change in energy
1/wavelength = RZ^2(n1^-2 - n2^-2)

Change in energy = -13.6(n1^-2 - n2^-2)

Question 8

Luminosity of an object

Answer 8

=AreaStefan-Boltzmann constT(effective)^4

T(effective) temperature as determined by a black body curve when the plot is fitted to luminosity - temperature assuming a perfect black body

Fitted to shape = colour temp

Question 9

Volume of a hollow sphere (small thickness)

Answer 9

4Piradius^2*thickness

Question 10

Pressure equations

Answer 10

F/A=nkT=nvxpx=1/3n