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Question 23M.3.SL.TZ1.12

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Date May 2023 Marks available [Maximum mark: 4] Reference code 23M.3.SL.TZ1.12
Level SL Paper 3 Time zone TZ1
Command term Determine, Estimate, State Question number 12 Adapted from N/A
12.
[Maximum mark: 4]
23M.3.SL.TZ1.12

A distant galaxy emits light of wavelength 486 nm. The light received on Earth has wavelength 512 nm.

(a)

Determine the recession speed of the galaxy.

[2]

Markscheme

vc=512-486486 ✓

⇒ v = 1.6 × 104 «km s−1»

 

Accept 0.053 c.

Accept answer in m s−1.

Award [2] for BCA.

(b)

Estimate the distance to the galaxy in pc. Take the Hubble constant as 72 km s−1 Mpc−1.

[1]

Markscheme

d = vH = 1.6×10472 = 222 ≈ 220 «Mpc»

 

ECF from (a).

(c)

Astrophysicists continue to seek an accurate value of the Hubble constant. State the importance of this constant for cosmology.

[1]

Markscheme

it is important because it is related to the age of the universe ✓

it is important in testing models of the universe ✓

it is important for determining distances ✓