Understanding the Force of Attraction Between Masses

The question asks us to identify the specific force responsible for the attraction between all objects that have mass throughout the universe. It highlights this force particularly in the context of the Earth's pull on objects near its surface.

Analyzing the Options for Force of Attraction

Let's look at the forces mentioned in the options:

• Spring force: This force is associated with the deformation of elastic objects like springs. When a spring is stretched or compressed, it exerts a force proportional to the displacement, trying to return to its original shape. This is not the force of attraction between all masses.
• Mechanical force: This is a broad term often used to describe forces exerted through mechanical means, such as pushes, pulls, or forces involved in machines. While gravity can cause mechanical effects, "mechanical force" itself doesn't specifically define the universal attraction between masses.
• Gravitational force: This is the fundamental force of attraction that exists between any two objects with mass. The greater the masses of the objects and the closer they are, the stronger the gravitational force between them. This force is responsible for keeping planets in orbit around stars, moons around planets, and for the pull of the Earth on objects near its surface, which we commonly call gravity.
• Friction force: This force opposes motion (or attempted motion) between two surfaces that are in contact. It depends on the nature of the surfaces and the normal force pressing them together. It is not a force of attraction between all masses in the universe.

Identifying the Correct Force

Based on the definitions, the force that describes the attraction between all masses in the universe, including the Earth's pull on nearby bodies, is the gravitational force.

Sir Isaac Newton first described the law of universal gravitation, stating that every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Mathematically, this is often represented as:

\(F = G \frac{m_1 m_2}{r^2}\)

Where:

• \(F\) is the gravitational force between the two objects.
• \(G\) is the gravitational constant.
• \(m_1\) and \(m_2\) are the masses of the two objects.
• \(r\) is the distance between the centers of the two objects.

This universal attraction is precisely what the question describes.

Conclusion on Force of Attraction

The force of attraction between all masses in the universe, especially the attraction of the earth's mass for bodies near its surface, is indeed the gravitational force.

Revision Table: Gravitational Force Concepts

Additional Information: Other Fundamental Forces

Gravitational force is one of the fundamental forces of nature. The four known fundamental forces are:

• Gravitational Force: Weakest but acts over infinite distances; responsible for large-scale structure of the universe (planets, stars, galaxies).
• Electromagnetic Force: Acts between charged particles; responsible for light, electricity, magnetism, and the structure of atoms and molecules. Can be attractive or repulsive.
• Strong Nuclear Force: Strongest force but acts over very short distances within the nucleus; holds protons and neutrons together.
• Weak Nuclear Force: Acts over very short distances; responsible for certain types of radioactive decay.

The gravitational force is the only one among these fundamental forces that is solely attractive between masses.