The life cycle of a star

The table in Figure 16 shows some data about four stars.

State which star in the table in Figure 16 is most likely to become a Black Hole.

Using data from the table in Figure 16, give a reason for your answer to part (i).

In a nuclear fusion reaction, mass is converted into energy.

Describe what is meant by nuclear fusion.

The speed of light, c, is 3.0 × 10⁸m / s.

The energy radiated by the Sun in 1 second is 3.9 × 10²⁶J.

Calculate the decrease in the Sun’s mass equivalent to this energy.

State the unit with your answer.

Use the equation

decrease in mass =_........

*(c) There have been a number of theories about the origin and development of the Universe.

One theory about the origin and development of the Universe is The Big Bang Theory.

Discuss two pieces of evidence that support The Big Bang Theory.

Figure 8 shows two types of force that act in the Sun.

One type of force acts inwards, towards the centre of the Sun.

The other type of force acts outwards, away from the centre of the Sun.

Outward forces are a result of nuclear fusion in the Sun.

State what causes the inward forces.

The inward and outward forces in stars like the Sun stay balanced for 10 billion years.

In the Sun, these forces have been balanced for 46 % of this time.

Calculate for how many billions of years these forces have been balanced in the Sun.

time =_........ billion years

Describe what will happen to the Sun when the inward and outward forces become unbalanced.

Nuclear fusion reactions take place in the Sun.

Describe what happens in a nuclear fusion reaction.

In 1989, two scientists claimed that they could produce a nuclear fusion reaction in their laboratory.

They said their reaction could take place at room temperature in a test tube.

Explain why other scientists did not believe them.

Figure 19 shows two objects, E and D.

E emits a sound.

D detects the sound.

E is moving in the direction shown by the arrow, but D is not moving.

E emits a sound of wavelength 1.86 m.

D measures the wavelength of this sound as 1.98 m.

Calculate the difference between the wavelength that E emits and the wavelength that D detects.

The velocity of sound is 330 m / s.

Calculate the velocity of E.

Use the equation

The wavelength of light emitted from distant galaxies is different when the light is detected on Earth.

Explain how this difference in wavelength shows that the Universe is expanding.

CMB radiation provides evidence that the Universe had a definite beginning.

Use the table in Figure 20 to give a typical value for the wavelength of CMB radiation.

During the evolution of a star, the nebula collapses and becomes a main sequence star.

State what causes the nebula to collapse.

Explain why the nebula stops collapsing as it becomes a main sequence star.

Figure 6 shows two objects, E and D.

E emits a sound.

D detects the sound.

E is moving in the direction shown by the arrow, but D is not moving.

E emits a sound of wavelength 1.86 m.

D measures the wavelength of this sound as 1.98 m.

Calculate the difference between the wavelength that E emits and the wavelength that D detects.

The velocity of sound is 330 m / s.

Calculate the velocity of E.

Use the equation

The wavelength of light emitted from distant galaxies is different when the light is detected on Earth.

Explain how this difference in wavelength shows that the Universe is expanding.

CMB radiation provides evidence that the Universe had a definite beginning.

Use the table in Figure 7 to give a typical value for the wavelength of CMB radiation.

During the evolution of a star, the nebula collapses and becomes a main sequence star.

State what causes the nebula to collapse.

Explain why the nebula stops collapsing as it becomes a main sequence star.

This question is about stars.

Use words from the box to complete the following sentences.

Stars of similar mass to our Sun were formed from a cloud of gas and dust

Our Sun is a_........ star.

Which will be the next stage in the evolution of our Sun?

The core of a star with a much bigger mass than our Sun is most likely to end as a

A nuclear fusion reaction is happening in our Sun.

The nuclear fusion reaction produces helium and radiates energy.

State one of the conditions necessary for this nuclear fusion reaction to start.

Describe what happens in this nuclear fusion reaction.

The intensity of the Sun’s radiation in W/m² on the surface of Earth is 1.3210³.

The intensity of the Sun’s radiation in W/m² on the surface of Mars is 4.9210².

Calculate the ratio

intensity of the Sun’s radiation on the surface of Earth intensity of the Sun’s radiation on the surface of Mars

The Sun has a mass of 2.0 × 10³⁰kg. A white dwarf has a mass of 3.4 × 10²⁹kg.

Calculate the value of

mass of this white dwarf

Figure 18 is a diagram giving some information about main sequence stars. Luminosity is a measure of how bright something is. An increase in luminosity means an increase in brightness.

Estimate the temperature of the Sun.

State how the brightness of a main sequence star changes with its temperature.

State how the brightness of a main sequence star changes with its mass.

Nuclear fusion provides the energy source for stars including the Sun.

Describe what happens during nuclear fusion.

A nebula may evolve into a main sequence star, such as the Sun.

Explain how a nebula may evolve into a main sequence star.

Equations

The Sun has a mass of 2.0 × 10³⁰kg. A white dwarf has a mass of 3.4 × 10²⁹kg.

Calculate the value of

mass of this white dwarf

Figure 4 is a diagram giving some information about main sequence stars. Luminosity is a measure of how bright something is. An increase in luminosity means an increase in brightness.

Estimate the temperature of the Sun.

State how the brightness of a main sequence star changes with its temperature.

State how the brightness of a main sequence star changes with its mass.

Nuclear fusion provides the energy source for stars including the Sun.

Describe what happens during nuclear fusion.

A nebula may evolve into a main sequence star, such as the Sun.

Explain how a nebula may evolve into a main sequence star.

Stars may originate as a nebula.

Describe the process that then occurs to produce the conditions necessary for nuclear fusion in a new star.

The energy, E, released in nuclear fusion is equivalent to loss in mass, m, according to the equation.

where c is the velocity of light.

c = 3.0010⁸ m/s

In 1 second, the energy radiated by the Sun is 3.8610²⁶ J.

Calculate the loss in mass of the Sun in 1 second.

*(b) The Big Bang theory gives an explanation for the origin of the Universe.

Explain how evidence supports the ideas that

● the Universe is expanding

● the Universe began at a single point.

A star has evolved to become a neutron star.

The mass, M, of the neutron star, of radius R, is given by

Use the equation to calculate the value for R.