Acontact force exists between two interacting objects that physically contact each other. a non-contact force exists when two interacting objects are not in physical contact but can still influence each other. true false

True.

A contact force is a force between two objects that are physically in contact with each other: an example of a contact force is the normal reaction of a table supporting a book.

A non-contact force is a force between two objects that are not physically in contact with each other: an example of non-contact force is the gravitational attraction between the Earth and the Moon.

TRUE

Explanation:

Contact force is due to physical contact of two bodies

This force is due to interaction of two contact surfaces

This contact force is perpendicular to the surface at contact point always

Now for non contact force we know that two or more bodies can exert force on each other either by field force.

This field force can exert push or pull from distance when two bodies are not in contact with each other.

So the statement given here is TRUE

Important thing is that all unitless quantity is dimensionless quantity. ... A dimensionless physical quantity may have an unit (e.g. Mechanical equivalent of heat) but a unitless physical quantity is always dimensionless (e.g. Coefficient of friction , refractive index