Paper 2 Model Answers

Question 1

State what is meant by binding energy [2]

Answer 1

[1] Energy equivalent to the mass deficit

[1] When nucleons bind together to form an atomic nucleus

Question 2

Case Example: e.g spheres in buildings to reduce simple harmonic motion

Answer 2

[1] The oscillating frame causes the lead spheres to deform plastically
[1] And this removes energy from the oscillating frame
[1] So the amplitude of oscillations decreases with time

OR

[1] Spheres collide/vibrate
[1] Hence energy is dissipated
[1] So the amplitude of oscillations decreases with time

Question 3

Substance being heated but no temperature change (molecular energy changes) [2] e.g tomato puree

Answer 3

[1] the temperature is constant when the puree boils because the average kinetic energy of the molecules in the puree is constant
[1] when boiling occurs, the thermal energy supplied increases the potential energy of the molecules causing the molecules to move further apart (producing steam) OR when boiling occurs, the thermal energy supplied increases the potential energy of the
molecules breaking molecular bonds

Question 4

Test for two identical polarising filters [2] e.g pair of identical sunglasses

Answer 4

[1] Pass light through one lens of the glasses and view the light through the lens of the second pair of glasses. Rotate one pair of glasses through 90°
[1] If the light intensity varies then the glasses use polarising filters

Question 5

Explain how quantisation of applies to the emission of radiation of energy from a black body [2]

Answer 5

[1] quantisation of energy is the idea that energy is emitted/radiated in discrete packets/photons
[1] each photon has an energy which is related to frequency OR suitable reference to E = hf

Question 6

Explain how Hubble’s observations support the conclusion that the universe is expanding and assess the reliability of this conclusion on the basis of Hubble’s original data [5]

Answer 6

[1] The wavelength change is bigger the further away the galaxies are
[1] The further away galaxies are the faster they are moving, so all distant galaxies are moving away from each other (and the universe is expanding)
[1] There is a large amount of scattering in Hubble’s original data set.
[1] The original data set covers a very small range of distances [only the closest galaxies considered]
[1] Hence, on the basis of the original data, the conclusion drawn by Hubble was quite speculative