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Date May 2015 Marks available 2 Reference code 15M.3.HL.TZ1.16
Level Higher level Paper Paper 3 Time zone Time zone 1
Command term Outline Question number 16 Adapted from N/A

Question

This question is about general relativity.

Calculate the Schwarzschild radius for an astronomical object of mass 5.0 ×1030 kg.

[2]
a.

A spaceship is travelling towards the object in (a). The spaceship moves in a straight line such that its distance of closest approach would be about 107m. Discuss why the presence of the object in (a) will not significantly affect the motion of the spaceship.

[2]
b.

An observer, when viewing a distant galaxy, sees two images of the galaxy separated by a small angle. A massive star is positioned between the observer and the galaxy. Outline how these observations give support to the theory of general relativity.

[3]
c.

Markscheme

\(\left( {R = \frac{{2GM}}{{{c^2}}}} \right)\frac{{2 \times 6.7 \times {{10}^{ - 11}} \times 5.0 \times {{10}^{30}}}}{{9 \times {{10}^{16}}}}\);

=7.4×103 (m);

a.

closest approach much larger than R;
so Newtonian mechanics will apply;
spacetime will not be significantly warped;

b.

theory predicts that warping of spacetime will affect light;
the massive star is warping spacetime;
causing the light to bend around it;
Award [2 max] to an answer that addresses the last two marking points.
Accept answer to the last two marking points in a form of labelled diagram.

 

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Option A: Relativity » Option A: Relativity (Additional higher level option topics) » A.5 – General relativity (HL only)
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