Which of the following describes a non-contact force?

A non-contact force is characterized by its ability to exert influence on an object without any physical interaction between the objects involved. This definition aligns perfectly with the correct choice, which states that a non-contact force acts on an object without direct physical touch. Fundamental examples of non-contact forces include gravitational force, electromagnetic force, and nuclear force. These forces can have significant effects on objects while being separated by a distance.

In contrast, the other options highlight different aspects of forces. The first option describes a contact force, which specifically requires direct interaction between two objects to be experienced, such as friction or normal force. The third option incorrectly narrows the definition of force by suggesting that a non-contact force can only push objects; in reality, non-contact forces can also pull or attract, as seen in gravitational and magnetic interactions. Finally, the fourth option refers to mechanical advantage, which is related to how machines can amplify force in physical interactions, rather than describing a force that operates without contact.

This understanding reinforces the essence of non-contact forces as fundamental interactions that do not require the physical proximity of the objects involved.