Topic 4 - Astrophysics and Cosmology

Question 1

Differences and similarities between electric fields and gravitational fields

Answer 1

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Question 2

Electric fields are both attractive and repulsive while gravitational fields are always attractive
Electric fields are stronger than gravitational fields

Answer 2

However they are both radial from a point

Question 3

Flat universe

Answer 3

When the universe expands to a constant size

Question 4

Closed universe

Answer 4

The universe will stop expanding at some point and then collapse again

Question 5

Open universe

Answer 5

Universe could continue expanding forever

Question 6

Scientists can’t calculate the density of the universe

Answer 6

We can measure the mass of all the stars in the galaxy from its luminosity

Question 7

Galaxies rotate which means that all the stars they contain must be experiencing a centripetal force towards the Centre of the galaxy’s rotation.

Answer 7

When the rotational speed is measured, the mass suggested by the luminosity calculations is not nearly enough to create the centripetal force needed to keep the Galaxy spinning

Question 8

This suggests that the galaxies must contain a lot of mass that does not emit light

Answer 8

No one knows what the dark matter could be