# Worksheet: Motion of Planets, Moons, and Satellites

In this worksheet, we will practice describing the velocities and accelerations of planets, moons, and man-made satellites that are moving along circular orbits.

Q1:

The Americom-7 satellite was launched on September 14, 2000, and currently orbits Earth at a distance of 35,800 km above the surface. The EOS PM-1 satellite was launched on May 4, 2002, and currently orbits Earth at a distance of 702 km above the surface. Which satellite orbits Earth faster?

• AEOS PM-1
• BAmericom-7

Q2:

Above what line of latitude or longitude do geostationary satellites orbit?

• AThe equator
• B longitude
• CThe Tropic of Capricorn
• DThe Tropic of Cancer
• EThe prime meridian

Q3:

The diagram shows two different possible orbits of an object around a star. Which of the following correctly describes the shape of orbit (a)?

• AHighly elliptical
• BSpiral
• CHelical
• DCircular
• EElliptical

Which of the following correctly describes the shape of orbit (b)?

• ASpherical
• BHighly elliptical
• CSpiral
• DHelical
• ECircular

Q4:

Communication satellites are often placed into geostationary orbits. Why is this?

• AGeostationary orbit is the maximum height at which satellites can orbit without leaving the orbit of Earth. Satellites orbit at this height because it is where there is the most space; thus, the satellites will not crash into each other.
• BA geostationary orbit is the most energy-efficient orbit; thus, it is cheaper to keep a satellite in geostationary orbits than other orbits.
• CA satellite in geostationary orbit stays at the same point in the sky, making it easier to locate the satellite and send and receive signals.
• DGeostationary orbit is the lowest height at which satellites can orbit; thus, it is easier to place a satellite into a geostationary orbit.
• EA satellite in geostationary orbit stays at the same point in the solar system relative to the Sun; thus, the position of the satellite does not need to be tracked.

Q5:

Planets that orbit closer to a star move around the star. Planets that orbit farther away from a star move around the star.

• Afaster, slower
• Bslower, faster

Q6:

What is the period of the orbit of a geostationary satellite?

Q7:

Earth orbits the Sun at a distance of km. Venus orbits the Sun at a distance of km. Which planet is moving faster around the Sun?

• AVenus
• BEarth

Q8:

The diagram shows four planets orbiting a star. All of the planets have circular orbits. Which planet is moving the fastest?

• APlanet 1
• BPlanet 3
• CPlanet 4
• DPlanet 2

Which planet is moving the slowest?

• APlanet 1
• BPlanet 3
• CPlanet 4
• DPlanet 2

Is Planet 3 moving faster than, slower than, or at the same speed as Planet 2?

• AFaster
• BSlower
• CAt the same speed

Q9:

The diagram shows the orbit of a comet around the Sun. The comet takes 84 years to complete one full orbit. Calculate the time period of the comet’s orbit in seconds. Use a value of 365 for the number of days in a year. Give your answer in scientific notation to 3 significant figures.

• A s
• B s
• C s
• D s

At which point in the comet’s orbit will its speed be greatest?

• AWhen it is farthest from the Sun
• BWhen it is closest to the Sun

Q10:

The table shows the heights at which three satellites orbit Earth. Each satellite follows a circular orbit.

 Satellite Height above Earth’s Surface Terra ICESat-2 Eutelsat 113 West A 709 km 496 km 35,800 km

Which satellite takes the longest time to orbit Earth?

• AEutelsat 113 West A
• BTerra
• CICESat-2

Which satellite takes the shortest time to orbit Earth?

• AICESat-2
• BEutelsat 113 West A
• CTerra

Eutelsat 113 West A is a geostationary satellite. How long does it take to orbit Earth?

Q11:

The table shows the orbital periods of three satellites in orbit around Earth. Each satellite follows a circular orbit.

 Satellite Orbital Period Americom-8 NOAA-15 Jason-2 24 hours 101 minutes 113 minutes

Which satellite is closest to Earth?

• AAmericom-8
• BNOAA-15
• CJason-2

Which satellite is farthest away from Earth?

• AAmericom-8
• BJason-2
• CNOAA-15

Which satellite is in geostationary orbit?

• AAmericom-8
• BJason-2
• CNOAA-15

Q12:

Satellite A orbits Earth in 12 hours. Satellite B orbits Earth in 2 hours. Which satellite is closer to Earth?

• ASatellite B
• BSatellite A

Q13:

A geostationary satellite orbits Earth with a period of hours. Geostationary satellites orbit about 36,000 km above the , moving in the same direction as the Earth’s spin.

• A12, Tropic of Capricorn
• B12, equator
• C48, North Pole
• D24, South Pole
• E24, equator

Q14:

The diagram shows a planet orbiting a star. The planet has a circular orbit. shows the direction of the gravitational force acting on the planet, and shows the direction of the velocity of the planet. As the planet orbits the star, the magnitude of the velocity , but the direction of the velocity .

• Aincreases, does not change
• Bdecreases, does not change
• Cdecreases, change
• Dstays the same, changes
• Eincreases, change

As the planet orbits the star, the magnitude of its acceleration , but the direction of the acceleration .

• Bdecreases, does not change
• Cincreases, changes
• Dstays the same, changes
• Eincreases, does not change

In which direction is the acceleration of the planet as it orbits the star?

• AAlong the path of the orbit
• BToward the star
• CPerpendicular to the direction of the star from the planet
• DAway from the star

What is the angle between the velocity of the planet and its acceleration?

Q15:

Which of the four diagrams correctly shows the direction of the velocity of a planet, at any one moment in time, as it orbits a star? • A(c)
• B(b)
• C(a)
• D(d)

Q16:

Planets in a solar system are kept in orbit by the force of gravity acting between the planets and the star. In which direction does the force of gravity between the star and a planet pull the planet?

• AAway from the star
• BToward the center of the planet
• CToward the star
• DAlong the path of the orbit
• EPerpendicular to the direction of the star from the planet

Q17:

In a solar system, gravity acts between the star and the planets to keep the planets in orbit. Which of the four diagrams correctly shows the direction of the force of gravity acting upon the planet as it moves in a circular orbit? • A(b)
• B(a)
• C(c)
• D(d)

Q18:

A planet orbiting closer to a star experiences a force of attraction to the star due to gravity. A planet orbiting farther away from a star experiences a force of attraction to the star due to gravity.

• Agreater, lesser
• Blesser, greater

Q19:

The diagram shows four planets orbiting a star. All four planets have the same mass, and all have circular orbits. Which planet experiences the greatest force of attraction to the star due to gravity?

• APlanet 3
• BPlanet 1
• CPlanet 2
• DPlanet 4

Which planet experiences the weakest force of attraction to the star due to gravity?

• APlanet 3
• BPlanet 2
• CPlanet 4
• DPlanet 1

Does Planet 3 experience a greater or lesser force of attraction to the star due to gravity than Planet 2 experiences?

• ALesser
• BGreater