5.4.3 Orbits of Planets and Satellites

• What do Kepler's Laws of Planetary Motion describe?

  Movement of planets
• What is the relationship between a planet's orbital period and semi-major axis according to Kepler's Law of Periods?

  $T^{2} \propto a^{3}$
• The gravitational force between a planet and the Sun causes the planet to sweep equal areas in equal times.


  True
• What does Newton's Law of Universal Gravitation describe?

  Attractive force between masses
• Circular orbits are perfectly circular in shape.

  True
• In an elliptical orbit, potential and kinetic energy vary.


  True
• Order the steps to describe the relationship between the mass of the central body and orbital period:

  1️⃣ Larger mass of central body

  2️⃣ Shorter orbital period

  3️⃣ Faster orbital speed
• A greater orbital radius results in a longer orbital period.

  True
• What does the Law of Areas describe about a planet's speed?

  Faster when closer
• What is the role of gravitational force in orbital motion?

  Drives orbital motion
• What are satellites kept in their orbits by?

  Gravity
• Navigation satellites use a medium Earth orbit to provide timing information.
• Why are geostationary orbits useful for satellites?

  They remain stationary
• Match the type of artificial satellite with its use:

  Communication ↔️ Relay signals

  Navigation ↔️ Positioning information

  Earth Observation ↔️ Monitor climate

  Scientific Research ↔️ Conduct experiments
• Planets orbit the Sun in ellipses, with the Sun at one focus
• Kepler's Laws are derived empirically and do not explain the underlying forces
• The gravitational force is the key physical mechanism driving the orbital motion described by Kepler's laws
• The relationship between a planet's orbital period and semi-major axis can be derived from the gravitational force
• What is the eccentricity of a circular orbit?

  0
• Match the orbit type with its characteristic:

  Circular Orbit ↔️ Constant speed

  Elliptical Orbit ↔️ Variable speed
• The larger the mass of the central body, the shorter the orbital period
• Match Kepler's Laws with their descriptions:

  Law of Ellipses ↔️ Planets move in ellipses

  Law of Areas ↔️ Equal areas in equal times

  Law of Periods ↔️ T^2 ∝ a^3
• The Law of Periods relates orbital period to the semi-major axis.


  True
• Match the orbit type with its characteristic:

  Circular Orbit ↔️ Zero eccentricity

  Elliptical Orbit ↔️ Non-zero eccentricity
• Geostationary orbits allow satellites to remain stationary over a fixed point on Earth.


  True
• Earth observation satellites use low Earth orbits to monitor climate and weather.


  True
• Satellites are kept in their paths by the force of gravity.
• Which laws are used to predict satellite motion?

  Kepler's and Newton's Laws
• What is the formula to calculate a satellite's orbital speed?

  $v =$$\frac{2\pi r}{T}$
• The orbital speed of a satellite is calculated using its orbital radius and period.
• As the orbital radius increases, the orbital period increases at a faster rate.


  True
• What is the orbital speed of a satellite in low Earth orbit with a radius of 6,800 km and a period of 90 minutes?

  7.8 km/s
• What is the orbital speed of a satellite in a geostationary orbit with a radius of 42,164 km and a period of 24 hours?

  3.1 km/s
• A planet moves faster when it is closer to the Sun.

  True
• What is the fundamental force governing orbital motion according to Newton's Law of Universal Gravitation?

  Gravitational force
• Kepler's Laws explain the underlying forces of planetary motion.

  False
• Despite variations in speed and energy, angular momentum remains constant
• Circular orbits have objects moving at a constant speed
• What are the two main factors that affect orbital period and speed?

  Mass and radius
• What is the relationship between orbital radius and orbital speed?

  Inverse