cosmology

A graph of red shift against distance in metres was plotted for a range of nearby galaxies. The value of the gradient of the graph was 5.4 × 10⁻²⁷. Which of the following expressions gives a value for the Hubble constant in s⁻¹?

• 5.4 × 10⁻²⁷

• 3 × 10⁸ / 5.4 × 10⁻²⁷

• 1 / (3 × 10⁸ × 5.4 × 10⁻²⁷)

• 3 × 10⁸ × 5.4 × 10⁻²⁷

A helium nucleus approaches a gold nucleus. An electric force and a gravitational force act on each nucleus. Which statement about these forces is not correct?

• The electric force between the nuclei is repulsive.

• The electric force is always smaller than the gravitational force.

• Both forces increase as the nuclei approach.

• The gravitational force between the nuclei is attractive.

Which of the following describes a standard candle?

• a star of known distance

• a star of known intensity

• a star of known luminosity

• a star of known mass

A star is moving away from the Earth. The wavelengths of spectral lines in the light received from the star are measured. These wavelengths are not the same as the wavelengths of the same lines measured from a source in the laboratory. Which of the following explains the difference in the wavelengths?

• The star emits light with a shorter wavelength.

• The star emits light with a longer wavelength.

• The light arrives at the Earth with a shorter wavelength.

• The light arrives at the Earth with a longer wavelength.

The Moon is gradually moving away from the Earth. The gravitational potential at the Earth due to the Moon, and the gravitational force between the Earth and the Moon, are both changing. Which row of the table is correct?

• Gravitational potential: decreases, Gravitational force: decreases

• Gravitational potential: increases, Gravitational force: decreases

• Gravitational potential: decreases, Gravitational force: increases

• Gravitational potential: increases, Gravitational force: increases

The Hertzsprung-Russell diagram below has an incomplete temperature scale. Which row of the table gives possible values for X and Y?

• A) X: 3000, Y: 9000

• B) X: 3000, Y: 12000

• C) X: 9000, Y: 3000

• D) X: 12000, Y: 3000

The letters W, X, Y, and Z represent stars at these positions on the diagram. Which of the following is part of a possible evolutionary path of a star?

• W → Y

• X → Y

• Y → W

• Y → Z

The letters W, X, Y and Z represent stars at these positions on the diagram.

Which of the following statements about stars in positions W, X, Y and Z is correct?

• W and Y have the same mass.

• W has a lower surface temperature than Z.

• Y is more massive than W.

• Y has a lower surface temperature than X.