An example of an alternative conception:
It is very common for people to believe a force is needed for a moving object to continue moving, and not come to a stop.
Of course, in practice, moving objects do tend to come to a halt,and vehicles such as cars and planes soon stop moving unless powered. However, in terms of overall force, an object will remain in its present state of motion unless acted upon by a net (that is, unbalanced) force.
So a stationary object* will remain station if not acted upon by a force, and a moving object* will continue to move in the same direction at the same speed unless acted upon by a net force (this is Newton's first law of motion- the law of inertia).
People commonly find the second situation counter-intuitive, and assume a moving object will eventually just stop of its own accord (having perhaps used up its 'impetus').
(* Whether an object is moving or not depends on one's frame of reference. A person standing on the surface of the earth observing a plane fly by will consider it in motion, but themselves to be at rest. Of course, the Earth spins on its axis, and orbits the Sun; which is moving through the galaxy in a great arc; which is receeding from most other galaxies. So, the observer is only at rest from one particular reference frame, even that might seem the most sensible one to apply.)
Read: Newton's first law
Read 'Poincaré, inertia, and a common misconception'
