What is an example of a non-contact force?

A non-contact force is a force that acts on an object without any physical contact between the objects involved. The gravitational force is a prime example of this, as it operates over distances. It is the force that attracts two bodies towards each other, such as the Earth pulling objects towards it. This means that even if you drop an object from a height, it will accelerate towards the ground due to the gravitational pull, despite being physically separated by distance.

In contrast, the other forces mentioned, such as frictional force, tension force, and normal force, all require physical contact between objects to exert their effects. For instance, friction occurs between surfaces in contact when they attempt to slide past one another, while tension and normal forces involve interactions where one object physically pulls or supports another in contact. Thus, gravitational force stands out as the only example in the list that truly fits the definition of a non-contact force.