Incorrect from past paper 1

Question 1

you dont say heat energy you say

Answer 1

thermal energy

Question 2

How do you explain redshift

Answer 2

(there is) an increase in wavelength (of light) (1)

shows galaxies are moving away (from Earth) (1)

Question 3

CMB is detected in the ________ region of the electromagnetic spectrum,

Answer 3

microwave

Question 4

Explain why the nebula stops collapsing as it becomes a main sequence star.

Answer 4

(gravity causing) increase in temperature (1)

(until hot enough for) fusion (1)

(until) balance (between gravity and fusion/thermal) (1)

Question 5

sound _______ ___ (when entering water) (1)
light ______ _____(when entering water) (1)

Answer 5

speedss up
slows down

Question 6

If you get a q like

Describe how the student should use the graph in Figure 15 to determine the critical angle for glass.

and we have a graph with the angle of i and angle r but not up to critical angle
wyd

Answer 6

It tells you to use the graph so it likely means to extend the curve to find critical angle

then elaborate for marks

Question 7

Explain why the temperature of a black surface reaches a constant temperature after increasing in temperature, even though the heater remains switched on.

Answer 7

P is absorbing radiation/(thermal) energy (1)

P is (also) emitting radiation/(thermal) energy (1)

(rate of) emission increases with temperature (1)

(temperature constant) when (rate of) emission = (rate of) absorption
(1)

Question 8

How do you find the change in momentum from before and after a collision (say its 0.8 kg m/s before and 0.6 after)

Answer 8

The object is using its momentum in opposite directions (say going right but when it bounces off the wall it goes left) so we can say the momentums are +80 and -60. So we can calculate change in momentum by doing -60 - 80 = -1.4 NOT 0.2