Which of the following are examples of non-contact forces?

Non-contact forces are interactions that do not require physical contact between objects to exert an influence. The correct choice includes gravitational force, electrostatic force, and magnetic force, all of which act at a distance.

Gravitational force is the attraction between two masses, such as Earth and an object near its surface, and it acts over a distance without the need for contact. Electrostatic force arises from the interaction between charged particles, where like charges repel and opposite charges attract each other, also working over a distance. Magnetic force occurs between magnets or moving charges, allowing them to exert force on each other without direct contact.

The other options consist solely of contact forces, which operate only when objects are touching each other. Frictional and applied forces depend on contact between surfaces, while normal and tension forces result from physical interactions between objects. Therefore, while contact forces are important in many physical scenarios, they do not exemplify the concept of non-contact forces that can act at a distance.