Solar system, Stability of Orbital Motions & Satellites (AQA GCSE Physics)

The Sun lies at the centre of our solar system, with all other bodies, such as planets, orbiting around it.

Give two similarities and one difference between the orbits of the planets.

Similarities:  ______________________

Difference: ______________________

The innermost planets of the solar system consist mainly of heavy elements.

Where did these heavy elements come from?

What does this tell us about the age of our solar system in comparison to the age of many other stars?

The life cycle of a star consists of many stages.

Describe how a star forms.

At some point during its early life a star will change from being a protostar to a main sequence star.

Explain the difference between a protostar and a main sequence star.

During their main sequence stage, stars exist in a stable state.

Explain why such stars are stable.

Describe, in as much detail as you can, the life of a star similar in size to the Sun.

Describe how a star much more massive than the Sun will change once it has reached the end of its stable period.

Stars release large amounts of energy through the process of nuclear fusion

Explain what is meant by nuclear fusion.

Why does this process result in the release of energy?

When hydrogen undergoes nuclear fusion there is a loss of mass of 0.7%.

The energy released during the reaction can be calculated using the equation:

Energy released = mass loss (speed of light)²

(Where the speed of light is 3 10⁸ m / s)

Calculate the energy released by the fusion of 1g of hydrogen

Many satellites move in circular orbits around the Earth.

Figure 1 below shows a satellite at two points in its orbits, with the velocity and resultant force at those points labelled.

Figure 1

Explain why the velocity of the satellite changes as it orbits the Earth.

In order to travel along a circular path a resultant force must pull the satellite towards the centre of the circle.

What provides the resultant force on the satellite?

State two factors that determine the size of the resultant force.

Figure 2 below (not to scale) shows the orbits of two satellites (A and B) about the Earth.

Satellite A completes one orbit of the Earth every 24 hours.

Satellite B completes one orbit of the Earth every 90 minutes

Which satellite would be most suited to the following purposes:

Figure 3 below gives data for four bodies in the outer solar system.

Figure 3

Uranus orbits the Sun at an average distance of 2900 million km.

Use the above fact along with Figure 3 to find the average orbital speed of Uranus.

Jupiter’s orbit about the Sun is circular in shape.

Use data from Figure 3 to calculate the distance travelled by Jupiter in one orbit.

Use data from Figure 3 to calculate the time taken for Jupiter to complete one orbit.

Figure 4 below shows the typical orbit of a planet.

Figure 4

Add a line to Figure 4 showing the orbit of a typical comet.

Add an X to the line you have drawn in Figure 4, indicating the point at which the comet will be travelling with the greatest speed.

Table 1 contains information on the mass of different stars.

Table 1

Compare the masses of Proxima Centauri and VY Canis Majoris to the Sun.

Explain how these differences will affect the time these stars can remain stable.

Describe what will happen to each of the stars after they leave the main sequence stage.

Higher Tier Only

The Hubble Space Telescope is in orbit around the Earth. It detects visible light from distant objects.

Name the force that keeps the telescope in orbit around the Earth.

The Hubble Space Telescope moves in a circular orbit. Its distance above the Earth’s surface is 560 km.

The radius of the Earth is 6400 km and the Hubble Space Telescope completes one orbit in 96 minutes. 

Calculate the Hubble Space Telescope's orbital speed in m/s.   

Use the equation:

Orbital speed = ........................ m/s

A different telescope also orbits the Earth, but does not move in a circular orbit. Its distance from the Earth and its speed change as it orbits the Earth.

It travels fastest when it is closest to the Earth.

Use ideas about energy to explain why.

Table 1 shows the 5 stages of the life cycle of a star that has a similar mass to the Sun. 

Table 1 

State and explain what happens in stage 2 of Table 1. 

Include details of the forces involved.

State and explain what happens in stage 4 of Table 1.

The average length of time a star stays in stage 3 is 10⁹ to 10¹¹ years. 

Explain why the star remains stable during stage 3 for this length of time.

For stars with much larger masses than our Sun, stages 1 to 3 in Table 1 are almost exactly the same as lower mass stars. For the later stages, 4 and 5, the processes begin to differ.

Compare and contrast the final two stages in stars with much larger masses than our Sun and stars with similar masses to our Sun.