Stars Like Sun

Question 1

Explain how a nebula may evolve into a main sequence star

Answer 1

An explanation to include any three from:
nebula as a cloud of gas/dust (1)
gas / atoms pulled together / towards each other (1)
by gravitational force (1) temperature increase (1)
hot enough for nuclear fusion (1)

Question 2

Newton’s third law, when applied to the collision of the rocket and the asteroid as shown in Figure 12, can be stated as follows:
The force exerted by the rocket on the asteroid is equal and opposite to the force exerted by the asteroid on the rocket.
Explain how this statement links to the conservation of momentum in the collision.

Answer 2

Question 3

Stage 2 of Stars like Sun

Answer 3

The force of gravity within a nebula pulls the particles closer together until it forms a hot ball of gas, know as protostar

As particles are pulled closer together the density of the protostar will increase

Question 4

Stage 3 of stars like sun

Answer 4

Main sequence star
Once the protostar becomes hot enough, thermal expansion from fusion reactions occur within its core and the force of gravity keeps the star in equilibrium.

At this point, the star is born, and it becomes a main-sequence star

During the main sequence, the star is in equilibrium and said to be stable

The inward force due to gravity is equal to the outward pressure force which results from the expanding hot gases inside the star

Question 5

Stage 4 of life cycle of stars like sun

Answer 5

Red giant
After several billion years the reactions in the star eventually die down as it runs out of fuel

This causes the core to shrink and heat up

The core will shrink because the inward force due to gravity will become greater than the outward force due to the pressure dies down

As the core shrinks, more reactions will cause the outer part of the star to expand
It will become a red giant
It is red because the outer surface starts to cool

Question 6

Stage 5 of stars like the sun

Answer 6

White Dwarf

The star will eventually become unstable and eject the outer layer of dust and gas as a planetary nebula

The core which is left behind will collapse completely, due to the pull of gravity, and the star will become a white dwarf

The white dwarf will be cooling down and as a result, the amount of energy it emits will decrease