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

**Q2: **

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

**Q3: **

Titan is the largest moon of Saturn. It has a roughly circular orbit and it orbits Saturn at a distance of 1,220,000 km with a period of 15.9 days. At what speed is Titan moving along its orbit? Give your answer in kilometers per second and to 2 significant figures.

**Q4: **

The table shows some data about Saturn’s moon, Titan. Using this data, calculate the orbital period of Titan around Saturn. Assume that Titan has a circular orbit. Give your answer in days to the nearest day.

Titan (Moon of Saturn) | |
---|---|

Diameter | km |

Orbital Radius | km |

Orbital Speed | 5.57 km/s |

Mass | kg |

**Q5: **

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

- AThe Tropic of Capricorn
- BThe Tropic of Cancer
- CThe prime meridian
- DThe equator
- E longitude

**Q6: **

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
- BElliptical
- CSpiral
- DCircular
- EHelical

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

- AHighly elliptical
- BHelical
- CSpiral
- DCircular
- ESpherical

**Q7: **

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

- AGeostationary orbit is the lowest height at which satellites can orbit; thus, it is easier to place a satellite into a geostationary orbit.
- 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 solar system relative to the Sun; thus, the position of the satellite does not need to be tracked.
- DA satellite in geostationary orbit stays at the same point in the sky, making it easier to locate the satellite and send and receive signals.
- EGeostationary 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.

**Q8: **

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

**Q9: **

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

**Q10: **

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

**Q11: **

The diagram shows four planets orbiting a star. All of the planets have circular orbits.

Which planet is moving the fastest?

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

Which planet is moving the slowest?

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

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

- AFaster
- BAt the same speed
- CSlower

**Q12: **

A satellite orbits Earth at an orbital radius of 7 720 km and moves at a speed of 7.2 km/s. The satellite has a circular orbit.

What is the circumference of the satellite’s orbit? Give your answer in kilometres to 3 significant figures.

What is the period of the satellite’s orbit? Give your answer in minutes to the nearest minute.

**Q13: **

A satellite orbits Earth at an orbital radius of km and moves at a speed of 3.1 km/s. The satellite has a circular orbit.

What is the circumference of the orbit of the satellite? Give your answer in kilometers to 3 significant figures.

What is the period of the satellite’s orbit? Give your answer in hours to the nearest hour.

**Q14: **

Which of the following is the correct formula for the orbital speed of a satellite following a circular orbit around a planet given its orbital radius and orbital period? represents the orbital period, represents the orbital speed, and represents the orbital radius.

- A
- B
- C
- D
- E

**Q15: **

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 closest to the Sun
- BWhen it is farthest from the Sun

**Q16: **

Mercury travels 364 million kilometers as it makes 1 full orbit around the Sun. Assuming that Mercury has a circular orbit, at what distance away from the Sun does Mercury orbit? Give your answer to 2 significant figures.

**Q17: **

Mars orbits the Sun at a distance of about . Assuming that Mars has a circular orbit, what is the distance traveled by the planet as it makes 1 full orbit around the Sun? Give your answer in scientific notation to 2 significant figures.

- A
- B
- C
- D km

**Q18: **

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

Satellite | Terra | ICESat-2 | Eutelsat 113 West A |
---|---|---|---|

Height above Earth’s Surface | 709 km | 496 km | km |

Which satellite takes the longest time to orbit Earth?

- ATerra
- BICESat-2
- CEutelsat 113 West A

Which satellite takes the shortest time to orbit Earth?

- AICESat-2
- BTerra
- CEutelsat 113 West A

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

**Q19: **

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

Satellite | Americom-8 | NOAA-15 | Jason-2 |
---|---|---|---|

Orbital Period | 24 hours | 101 minutes | 113 minutes |

Which satellite is closest to Earth?

- AAmericom-8
- BJason-2
- CNOAA-15

Which satellite is farthest away from Earth?

- AAmericom-8
- BNOAA-15
- CJason-2

Which satellite is in geostationary orbit?

- ANOAA-15
- BJason-2
- CAmericom-8

**Q20: **

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

- ASatellite B
- BSatellite A

**Q21: **

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.

- A48, North Pole
- B12, equator
- C24, South Pole
- D24, equator
- E12, Tropic of Capricorn

**Q22: **

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 .

- Adecreases, does not change
- Bincreases, does not change
- Cincreases, change
- Dstays the same, changes
- Edecreases, change

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

- Astays the same, changes
- Bincreases, changes
- Cdecreases, does not change
- Dincreases, does not change
- Edecreases, changes

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

- AToward the star
- BAway from the star
- CAlong the path of the orbit
- DPerpendicular to the direction of the star from the planet

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

**Q23: **

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(d)
- D(a)

**Q24: **

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?

- AAlong the path of the orbit
- BAway from the star
- CPerpendicular to the direction of the star from the planet
- DToward the star
- EToward the center of the planet

**Q25: **

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(d)
- B(a)
- C(c)
- D(b)