Space

Question 1

What do you have to consider when moving a mass in a gravitational field? (Taking different paths)

Answer 1

The same amount of energy is required as the energy required to move a mass between two points in a gravitational field is independent of the path taken.

Question 2

As a probe travels away from earth, what would happen to the clock running inside?

Answer 2

The clock on the provide runs faster as it is in a weaker gravitational field.

Question 3

State the name given to the series of fusion reactions that converts hydrogen to helium inside the core of some stars

Answer 3

The proton-proton chain

Question 4

There is a class of stars which will stay on the main sequence for thousands of billions of years. Why, despite knowing the mass of these stars have scientists not yet observed the fate of these stars?

Answer 4

Lifetime is greater than the age of the observable universe

Question 5

What two particles are the by-product of converting hydrogen to helium in a main sequence star (pp chain)

Answer 5

Electron neutrino, and positron

Question 6

State einsteins equivalence principle

Answer 6

It is impossible to tell the difference between the effects of a uniform gravitational field and a frame of reference which has a constant acceleration

Question 7

What is the difference between special and general relativity?

Answer 7

General relativity - Non inertial frames of reference
Special relativity- Inertial (accelerating) frames of reference

Question 8

Why would a spacecraft not need to reach a planets escape velocity to move into orbit?

Answer 8

The craft hasn’t left the gravitational field

The orbit of the craft isnt at infinity, the escape velocity enables an object to reach infinity

Question 9

When hydrogen fusion in its core stops, the sun will leave the main sequence and become a red giant.

Explain in terms of thermal pressure and gravitational forces, what happens to the radius of the sun as it becomes a red giant.

Answer 9

Radius increases because the forces due to thermal pressure are greater and gravitational force
Radius stops increasing when forces due to thermal pressure balance out gravitational forces

Question 10

Describe the proton proton chain in terms of reactions

Answer 10

Two protons fuse to make deuterium, also releasing a positron and neutrino

Deuterium and a proton fuse releasing a gamma raw photon and emitting a helium nucleus

Two helium 3 nuclei fuse to form a helium 4 nucleus and two free protons which may cause further proton-proton chains