Final answer:
The force of attraction between two objects is known as gravity, and it is a fundamental force responsible for the structure of galaxies. The electromagnetic force, in contrast, is responsible for holding an atom together and explains the sensation of touch and normal forces in daily life.
Step-by-step explanation:
The force of attraction between any two objects is known as gravity. Gravity is a fundamental force that attracts all objects with mass towards each other. This force is what gives weight to objects and is responsible for the structure of galaxies, keeping stars within galaxies and planets orbiting around stars, including our own planet's orbit around the Sun.
In contrast, the force responsible for holding an atom together is the electromagnetic force. This force involves the attraction and repulsion between electrically charged particles and is much stronger than gravity at atomic and molecular scales. When atoms and molecules touch, we feel this force as sensations of touch and tension, but we never actually feel gravity directly; gravity is sensed through electromagnetic interactions.
As for normal forces, they describe the support force exerted upon an object that is in contact with another stable object. For example, a book resting on a table experiences a normal force. This is best explained by electromagnetic repulsion, which is due to the electromagnetic force at the molecular level preventing the atoms of the book and the table from occupying the same space.