yr 13 revision - astrophysics

Two stars with the same luminosity might produce different radiation fluxes at Earth. This is primarily due to the stars having different

• diameters

• distances from the Earth

• motions through the Universe

• surface temperatures

The gravitational field strength at the surface of Mars is one third that at the surface of the Earth. A mass-spring system with a frequency of 3.0 Hz at the surface of the Earth would have a frequency at the surface of Mars of

• 5.2 Hz

• 3.0 Hz

• 1.7 Hz

• 1.0 Hz

Which of the following statements about the possible fate of the Universe is not correct?

• If the Universe is open then it will continue to expand forever.

• If the Universe is open then it will eventually reach a maximum size.

• If the Universe is closed then it will eventually reach a maximum size.

• If the Universe is closed then it will reach a maximum size and then contract.

A Hertzsprung-Russell diagram is plotted for an old star cluster. Compared with a young cluster containing a similar number of stars there will be fewer

• light main sequence stars.

• massive main sequence stars

• red giant stars.

• white dwarf stars.

About 25% of the mass of our Universe is thought to consist of dark matter. A key property of dark matter is that it

• absorbs all electromagnetic-radiation.

• cannot be detected.

• emits no detectable electromagnetic-radiation

• exerts no gravitational force.

Cosmologists describe the universe as being open, closed or flat. A closed universe is one which

• has always been the same size.

• has a maximum size.

• has an uncertain future.

• will expand forever.

In many ways electrical and gravitational forces are similar. One key difference is that only

• electrical forces can be attractive and repulsive.

• electrical forces have an infinite range.

• gravitational forces can be attractive and repulsive.

• gravitational forces have an infinite range.

Which letter A, B, C or D represents the region on the diagram where a white dwarf star would be shown

• A

• B

• C

• D

Which letter A,B,C or D represents the region on the diagram where our sun would be shown?

• A

• B

• C

• D

There is uncertainty in the value of the Hubble constant determined by astronomers because

• detailed observations have only been possible recently.

• distances to distant galaxies are uncertain.

• the age of the universe is uncertain.

• the Big Bang is only a theory.