Orbital motion and satellites

Figure 11 gives the values of gravitational field strength, g, on the surfaces of Earth, the Moon and Mars.

Calculate the ratio

A person has a weight of 730 N on Earth.

Calculate the person’s weight on the Moon, using information from Figure 11.

The gravitational field strength, g, is different on the surfaces of Earth, the Moon and Mars.

Explain why this is the case.

Asteroids have elliptical (oval) orbits around

*(c) Scientists have been searching beyond the Solar System to find planets where life could exist.

One requirement for life to exist on a planet is that there is water on the surface of the planet.

The planets where surface water could exist are in a region called the habitable zone.

Figure 12 is a diagram showing our Sun, with its five closest planets, and a more distant star with three of its planets labelled A, B and C. The habitable zone is shaded.

(Source adapted from: https://www.researchgate.net/publication/23993674_Darwin_-A_ Mission_to_Detect_and_Search_for_Life_on_Extrasolar_Planets/figures?lo=1)

Discuss the chance of life existing on the planets shown in Figure 12.

Your answer should refer to

• the five planets shown from our Solar System, giving the names of P, Q and R.

• the three planets, A, B and C, orbiting the more distant star.

Figure 10 shows a skier sliding down a slope.

The gravitational potential energy of the skier decreases by 39 000 J between the top and the bottom of the slope.

The mass of the skier is 70 kg.

Calculate the height, h of the slope.

The value of g is 10 N / kg.

Use the equation

Δ GPE = m × g × h

The skier starts from rest at the top of the slope.

The velocity of the skier at the bottom of the slope is 27 m / s.

Using information from Figure 10, calculate the acceleration of the skier along the slope.

acceleration =_........ m / s²

When the skier slides from the top to the bottom of the slope, some energy is dissipated.

Explain how to determine the amount of energy dissipated.

Figure 11 shows athletes running at a constant speed on a curved section of

Even though they are running at a constant speed, the velocity of each athlete is changing.

State why the velocity of each athlete is changing.

The athletes start the race on a straight section of track.

Figure 12 shows a distance / time graph for one of the athletes.

Determine the gradient of this graph at a time of 2.5 s.

gradient =_........

Figure 15 shows an artificial satellite in orbit around the Earth.

Which of these shows the direction of the force that keeps the satellite in orbit around the Earth?

The satellite travels at a constant speed around the Earth.

Explain why the satellite is accelerating even though it travels at a constant speed.

The Hubble Space Telescope is an artificial satellite in orbit about 500 km above the Earth’s surface.

This telescope is used to observe the light from very distant objects in the Universe.

Explain why the Hubble Space Telescope must be high above the Earth’s surface to make its observations.

There are many other artificial satellites in orbit around the Earth.

Figure 16 shows the time taken to complete one orbit for satellites at different heights above the Earth’s surface.

time to complete one orbit in minutes

Figure 16

Describe the relationship shown in Figure 16.

*(d) A long time ago, many people thought that the objects seen in the sky were arranged as shown in Figure 17.

Compare the arrangement shown in Figure 17 with what we now know about the Solar System.

Your answer should refer to

• the objects that are in the Solar System

• how these objects are arranged.

You may draw a diagram to help your answer.

Figure 13 shows a ball being rotated in a horizontal circle.

Which arrow in Figure 13 shows the direction of the centripetal force on the ball?

The ball is moving at constant speed. Give one reason why the velocity of the ball is continuously changing.

Figure 14 shows a gymnast landing on a mat and coming to rest.

The gymnast has a mass of 53 kg.

The gymnast lands on the mat with a velocity of 4.0 m/s.

The average force exerted by the mat on the gymnast is 3500 N.

Calculate the time taken for the gymnast to come to rest.

Give your answer to an appropriate number of significant figures.

Use the equation

* (c) Figure 15 shows two trolleys, P and Q, moving at the same speed, v, directly towards each other.

The trolleys have the same mass.

When the trolleys collide, they stick together and stop.

Explain how momentum and energy are both conserved in this collision.

A rock on the surface of the Earth has a mass of 12 kg.

Calculate the weight of this rock on the surface of the Earth.

The gravitational field strength on the surface of the Earth is 10 N/kg.

Use the equation

weight on the Earth =_........

The weight of the same rock on the surface of the Moon is 20 N.

Calculate the gravitational field strength on the surface of the Moon.

gravitational field strength on the Moon_........

*(b) Describe the Solar System in terms of the Sun, the planets, and the other objects which move in the Solar System.

Your answer should include the patterns of movement of the planets and the other objects in the Solar System.

You may draw a labelled diagram if it helps your answer.

The Asteroid Belt is part of our Solar System.

Vesta is an asteroid in the Asteroid Belt.

Vesta orbits the Sun between the orbits of

Vesta has an orbital speed of 1.9 × 10⁴ m/s.

Vesta travels a distance of 2.2 × 10¹² m when it orbits the Sun once.

Calculate the time taken for Vesta to orbit the Sun once.

Explain why Vesta is accelerating even when it is travelling at a constant speed.

Energy is transferred from the Sun to Vesta by radiation.

Explain why the temperature on Vesta does not continue to rise, even though it is absorbing energy from the Sun.

The distance between Vesta and the Sun is 2.4 AU.

1 AU is the distance between the Earth and the Sun.

The intensity of the Sun’s radiation reaching the Earth is 1400 W/m².

1 W = 1 J/s

The intensity of the Sun’s radiation at a distance, d, from the Sun is given by the equation

where K always has the same value.

State the unit of K.

Calculate the intensity of the radiation from the Sun at Vesta.

Which lens is a converging lens with the greatest power?

The equation that relates the power of a lens to the focal length of the lens is

The power of a lens is 5 dioptres.

Use the equation to calculate the focal length of the lens in cm.

Figure 3 shows a semicircular glass block.

Figure 3

Describe how a student could use the semicircular glass block and other apparatus to determine the critical angle for a glass‑air boundary.

You should add to the diagram in Figure 3 to help with your answer.

A long time ago, scientists believed that the Earth was at the centre of the Solar System.

Evidence has since proved that the Sun is at the centre of the Solar System.

State one other idea about the Solar System that has changed over time.

Figure 4 shows data for some of the planets of the Solar System.

distance from the Sun in millions of km

Figure 4

Ceres is an asteroid that orbits the Sun between Mars and Jupiter. It takes Ceres 4.6 Earth years to make one orbit of the Sun.

Use the graph to estimate the distance of Ceres from the Sun.

Show your working.

distance of Ceres from the Sun =_........ millions of km

The force that keeps an object moving in a circular path is known as the

Figure 11 shows an object moving in a circular path.

Draw an arrow on Figure 11 to show the direction of the force that keeps the object moving in a circular path.

The object in Figure 11 is moving at constant speed.

Explain why it is not moving with constant velocity.

Figure 12 shows a skier on a slope.

The skier travels down the slope with a constant acceleration.

The speed of the skier is measured at points P and Q.

The table in Figure 13 gives some data about the skier making one downhill run.

Calculate the distance from P to Q.

Use an equation selected from the list of equations at the end of this paper.

Calculate the time taken for the skier to travel from P to Q.

Which row of the table is correct for both force and velocity?

Figure 20 shows a satellite orbiting the Earth.

State the name of the force that keeps the satellite in orbit around the Earth.

Draw an arrow on Figure 20 to show the direction of the force acting on the satellite, that keeps the satellite in orbit around the Earth.

Label this arrow ‘F’.

Satellites are used to gather data about the origin of the Universe.

The Big Bang theory is a theory about the origin of the Universe.

Evidence for the Big Bang theory is provided by red‑shift and CMB radiation.

Describe what is meant by red‑shift.

Explain how red‑shift provides evidence for the Big Bang theory.

The Cosmic Background Explorer (COBE) satellite observed CMB radiation from 1989 to 1993.

State what the ‘M’ in CMB radiation stands for.

State what is meant by ‘cosmic background radiation’.

Explain how the presence of CMB radiation provides evidence for the Big Bang theory.

Which row of the table is correct for both force and velocity?

Figure 6 shows a satellite orbiting the Earth.

State the name of the force that keeps the satellite in orbit around the Earth.

Draw an arrow on Figure 6 to show the direction of the force acting on the satellite, that keeps the satellite in orbit around the Earth.

Label this arrow ‘F’.

Satellites are used to gather data about the origin of the Universe.

The Big Bang theory is a theory about the origin of the Universe.

Evidence for the Big Bang theory is provided by red-shift and CMB radiation.

Describe what is meant by red-shift.

Explain how red-shift provides evidence for the Big Bang theory.

The Cosmic Background Explorer (COBE) satellite observed CMB radiation from 1989 to 1993.

State what the ‘M’ in CMB radiation stands for.

State what is meant by ‘cosmic background radiation’.

Explain how the presence of CMB radiation provides evidence for the Big Bang theory.