What is the force of attraction between all masses in the universe?

• A. Friction
• B. Tension
• C. Gravitational force
• D. Electrostatic force

Answer: (C)

Gravity is the force of attraction that exists between all objects that have mass. This universal pull is what makes things fall toward Earth, keeps the Moon in orbit around Earth, and governs the motion of planets. The other terms you might hear—friction, tension, and electrostatic force—describe different types of forces: friction resists motion between surfaces in contact, tension is the pulling force along a string or rope, and electrostatic force is the attraction or repulsion between electric charges. Gravity, on the other hand, acts between any two masses and is always attractive, pulling them toward each other along the line connecting their centers. Its strength depends on the masses involved and the distance between them, summarized by the idea that greater mass and shorter distance produce a stronger gravitational attraction.