Question

Which force pulls the satellite toward Earth? A. the Moon's gravity B. Earth's gravity C. the Sun's gravity D. Earth's magnetic field

Short answer

B. Earth's gravity

Step-by-step solution

Identify the Type of Force

Satellites are held in orbit due to gravitational forces. Gravity is the force that attracts two bodies toward each other.

Determine the Dominant Gravitational Force

For a satellite orbiting Earth, the primary force affecting its motion is the gravitational attraction between the satellite and Earth, as Earth is the closest and most massive object in proximity.

Evaluate Other Forces

Although the Moon and Sun also exert gravitational forces, these are much weaker compared to Earth's gravity due to their greater distances from the satellite compared to Earth.

Clarify the Role of Magnetic Fields

While Earth does have a magnetic field, it does not contribute to the gravitational pull required to keep the satellite in orbit.

Choose the Correct Answer

Based on the above reasoning, the correct force that pulls the satellite toward Earth is Earth's gravity.

Key concepts

Gravitational Forces

All objects with mass exert a gravitational force on each other. This universal force is responsible for the attraction between two bodies.

• The strength of gravitational force depends on the masses of the objects involved and the distance between them, as described by Newton's Law of Universal Gravitation.
• The formula for gravitational force is given by \[ F = G \frac{m_1 m_2}{r^2} \] where \( F \) is the force of gravity, \( G \) is the gravitational constant, \( m_1 \) and \( m_2 \) are the masses, and \( r \) is the distance between the centers of the two masses.

Gravity not only keeps us on the ground but also governs the motion of celestial bodies, ensuring the orbits of planets, moons, and satellites.

Satellite Orbit

Satellites in orbit around Earth are influenced mainly by Earth's gravitational pull. As they travel around the planet:

• The balance between gravity and their tangential speed ensures they remain in a stable orbit.
• Without Earth's gravity, a satellite would travel in a straight line into space.
• Engineers calculate specific speeds and altitudes to achieve a desired orbit which can be geostationary (remaining over one location) or polar (moving from pole to pole).

This delicate balance results in predictable paths which are crucial for communication, weather forecasts, and scientific observations.

Magnetic Fields

Earth generates its own magnetic field, which extends into space and affects charged particles but not the trajectory of satellites directly.

• This magnetic field results from the movement of molten iron in the Earth’s outer core.
• It creates the magnetosphere, which shields us from the solar wind and is important for navigational tools like compasses.
• While some spacecraft are equipped to measure magnetic fields for scientific study, these fields do not contribute to the gravitational force necessary for maintaining satellite orbits.

Knowing the distinction between magnetic fields and gravitational forces helps clarify their unique roles in space science.

Earth Science

Earth science covers a wide range of topics concerning the structure and processes of our planet. It blends disciplines such as:

• Geology, which studies Earth's solid materials and processes.
• Meteorology, the science of the atmosphere and weather patterns.
• Oceanography, focusing on Earth's oceans and marine ecosystems.
• Astronomy, exploring celestial bodies and the universe which also includes understanding how gravity affects bodies in space like satellites.

Understanding Earth's gravitational force is key in Earth science as it impacts daily life, from holding our atmosphere in place to influencing tides.