DP Physics (last assessment 2024)

Test builder »

Question 18M.3.HL.TZ2.18a

Select a Test
Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.HL.TZ2.18a
Level HL Paper 3 Time zone TZ2
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 2]
18M.3.HL.TZ2.18a
(a)

Outline, with reference to the Jeans criterion, why a cold dense gas cloud is more likely to form new stars than a hot diffuse gas cloud.

[2]

Markscheme

«For a star to form»: magnitude of PE of gas cloud > KE of gas cloud

OR

Mass of cloud > Jean's mass

OR

Jean’s criterion is the critical mass

 

hence a hot diffuse cloud could have KE which is too large/PE too small

OR

hence a cold dense cloud will have low KE/high PE

OR

a cold dense cloud is more likely to exceed Jeans mass

OR

a hot diffuse cloud is less likely to exceed the Jeans mass

 

Accept Ep + Ek < 0

[2 marks]

Syllabus sections